In these days,the increasing massive data are being produced and demanded to be processed with the rapid growth of information technology.It is difficult to rely solely on the shrinking of semiconductor devices and sc...In these days,the increasing massive data are being produced and demanded to be processed with the rapid growth of information technology.It is difficult to rely solely on the shrinking of semiconductor devices and scale-up of the integrated circuits(ICs)again in the foreseeable future.Exploring new materials,new-principle semiconductor devices and new computing architectures is becoming an urgent topic in this field.Ambipolar two-dimensional(2D)semiconductors,possessing excellent electrostatic field controllability and flexibly modulated major charge carriers,offer a possibility to construct reconfigurable devices and enable the ICs with new functions,showing great potential in computing capacity,energy efficiency,time delay and cost.This review focuses on the recent significant advancements in reconfigurable electronic and optoelectronic devices of ambipolar 2D semiconductors,and demonstrates their potential approach towards ICs,like reconfigurable circuits and neuromorphic chips.It is expected to help readers understand the device design principle of ambipolar 2D semiconductors,and push forward exploring more new-principle devices and new-architecture computing circuits,and even their product applications.展开更多
Dual-metal gate and gate–drain underlap designs are introduced to reduce the ambipolar current of the device based on the C-shaped pocket TFET(CSP-TFET).The effects of gate work function and gate–drain underlap leng...Dual-metal gate and gate–drain underlap designs are introduced to reduce the ambipolar current of the device based on the C-shaped pocket TFET(CSP-TFET).The effects of gate work function and gate–drain underlap length on the DC characteristics and analog/RF performance of CSP-TFET devices,such as the on-state current(I_(on)),ambipolar current(I_(amb)),transconductance(g_(m)),cut-off frequency(f_(T))and gain–bandwidth product(GBP),are analyzed and compared in this work.Also,a combination of both the dual-metal gate and gate–drain underlap designs has been proposed for the C-shaped pocket dual metal underlap TFET(CSP-DMUN-TFET),which contains a C-shaped pocket area that significantly increases the on-state current of the device;this combination design substantially reduces the ambipolar current.The results show that the CSP-DMUN-TFET demonstrates an excellent performance,including high I_(on)(9.03×10^(-4)A/μm),high I_(on)/I_(off)(~10^(11)),low SS_(avg)(~13 mV/dec),and low I_(amb)(2.15×10^(-17)A/μm).The CSP-DMUN-TFET has the capability to fully suppress ambipolar currents while maintaining high on-state currents,making it a potential replacement in the next generation of semiconductor devices.展开更多
In the present paper, based on the conservation law of mass and momentum for ion and electron, the distribution of velocity, density of ions and electrons along radial direction are solved numerically. Furthermore, th...In the present paper, based on the conservation law of mass and momentum for ion and electron, the distribution of velocity, density of ions and electrons along radial direction are solved numerically. Furthermore, the comparison between MHD properties of ambipolar and qua- si- ambipolar diffusion is made. The numerical calculation is carried out for argon plasma. The results show that the ion density, ratio of ion and electron velocity at the cathode sheath boundary surface in- crease with the intensity of magnetic induction, meanwhile, the distance between sheaths decreases as well as the radial velocity of ion and electron at the anode sheath boundary. The ion density varies in accord with experiment qualitatively. All parameters mentioned above are not sensitive to magnetic field in ambipolar diffusion.展开更多
Fabrication of ambipolar organic field-effect transistors (OFETs) is essential for the achievement of an organic complementary logic circuit. Ambipolar transports in OFETs with heterojunction structures are realized...Fabrication of ambipolar organic field-effect transistors (OFETs) is essential for the achievement of an organic complementary logic circuit. Ambipolar transports in OFETs with heterojunction structures are realized.We select pentacene as a P-type material and N,N'-bis(4-trifluoromethylben-zyl)perylene-3,4,9,10-tetracarboxylic diimide (PTCDI-TFB) as a n-type material in the active layer of the OFETs.The field-effect transistor shows highly air-stable ambipolar characteristics with a field-effect hole mobility of 0.18 cm^2/(V·s) and field-effect electron mobility of 0.031 cm^2/(V·s).Furthermore the mobility only slightly decreases after being exposed to air and remains stable even for exposure to air for more than 60 days.The high electron affinity of PTCDI-TFB and the octadecyltrichlorosilane (OTS) self-assembly monolayer between the SiO2 gate dielectric and the organic active layer result in the observed air-stable characteristics of OFETs with high mobility.The results demonstrate that using the OTS as a modified gate insulator layer and using high electron affinity semiconductor materials are two effective methods to fabricate OFETs with air-stable characteristics and high mobility.展开更多
A tunnel field-effect transistor(TFET) is proposed by combining various advantages together, such as non-uniform gate-oxide layer, hetero-gate-dielectric(HGD), and dual-material control-gate(DMCG) technology. The effe...A tunnel field-effect transistor(TFET) is proposed by combining various advantages together, such as non-uniform gate-oxide layer, hetero-gate-dielectric(HGD), and dual-material control-gate(DMCG) technology. The effects of the length of non-uniform gate-oxide layer and dual-material control-gate on the on-state, off-state, and ambipolar currents are investigated. In addition, radio-frequency performance is studied in terms of gain bandwidth product, cut-off frequency,transit time, and transconductance frequency product. Moreover, the length of non-uniform gate-oxide layer and dualmaterial control-gate are optimized to improve the on-off current ratio and radio-frequency performances as well as the suppression of ambipolar current. All results demonstrate that the proposed device not only suppresses ambipolar current but also improves radio-frequency performance compared with the conventional DMCG TFET, which makes the proposed device a better application prospect in the advanced integrated circuits.展开更多
A new T-shaped tunnel field-effect transistor(TTFET) with gate dielectric spacer(GDS) structure is proposed in this paper. To further studied the effects of GDS structure on the TTFET, detailed device characteristics ...A new T-shaped tunnel field-effect transistor(TTFET) with gate dielectric spacer(GDS) structure is proposed in this paper. To further studied the effects of GDS structure on the TTFET, detailed device characteristics such as current-voltage relationships, energy band diagrams, band-to-band tunneling(BTBT) rate and the magnitude of the electric field are investigated by using TCAD simulation. It is found that compared with conventional TTFET and TTFET with gate-drain overlap(GDO) structure, GDS-TTFET not only has the minimum ambipolar current but also can suppress the ambipolar current under a more extensive bias range. Furthermore, the analog/RF performances of GDS-TTFET are also investigated in terms of transconductance, gate-source capacitance, gate-drain capacitance, cutoff frequency, and gain bandwidth production. By inserting a low-κ spacer layer between the gate electrode and the gate dielectric, the GDS structure can effectively reduce parasitic capacitances between the gate and the source/drain, which leads to better performance in term of cutoff frequency and gain bandwidth production. Finally, the thickness of the gate dielectric spacer is optimized for better ambipolar current suppression and improved analog/RF performance.展开更多
A mathematical model and experimental analysis of the impact of oxide thickness on the ambipolar conduction in Schottky Barrier Carbon Nanotubes(CNTs)Field Effect Transistor(SB CNTFETs)is presented.Suppression of ambi...A mathematical model and experimental analysis of the impact of oxide thickness on the ambipolar conduction in Schottky Barrier Carbon Nanotubes(CNTs)Field Effect Transistor(SB CNTFETs)is presented.Suppression of ambipolar conduction in SB CNTFETs is imperative in order to establish them as the future of IC technology.The ambipolar nature of SB CNTFETs leads to a great amount of leakage current.Employing a gate oxide dielectric of thickness,tox^50 nm suppresses the ambipolar behavior.In an SB CNTFET,it is the electric field at the source/drain contacts that control the conductance and the band bending length at the contacts is defined by tox.Therefore,tox is the prime parameter that influences the width of the Schottky barrier and the current in the subthreshold region.Due to the wide SB,there is a loss in on-current due to tunneling,but the current due to thermionic emission is increased by employing a high-κdielectric such as Zirconium dioxide(ZrO2).This work proposes an approach to suppress ambipolar behavior in SB CNTFETs without decreasing the on current.The thickness and dielectric constant of the gate oxide are optimized using the particle swarm optimization(PSO)algorithm to achieve suppression of ambipolar conduction without any loss in on-current.The proposed SB CNTFET was modeled using Verilog-A.Experimental demonstration of the suppression of ambipolar property is also presented.Two SB CNTFETs are fabricated using high-κdielectric such as ZrO2 with different thickness.A device with thin(~5 nm)gate oxide and another device with thick(~50 nm)gate oxide were fabricated.From the experimental results,it is observed that the device with the thin gate oxide exhibited ambipolar characteristics and the device with the thick gate oxide did not exhibit ambipolar characteristics.The increase in thickness,tox,ensures suppression of ambipolar behavior.展开更多
This work reports on the integration of organic and inorganic semiconductors as heterojunction active layers for high-performance ambipolar transistors and complementary metal-oxide-semiconductor(CMOS)-like inverters....This work reports on the integration of organic and inorganic semiconductors as heterojunction active layers for high-performance ambipolar transistors and complementary metal-oxide-semiconductor(CMOS)-like inverters.Pentacene is employed as a p-type organic semiconductor for its stable electrical performance,while the solution-processed scandium(Sc)substituted indium oxide(ScInO)is employed as an n-type inorganic semiconductor.It is observed that by regulating the doping concentration of Sc,the electrical performance of the n-type semiconductor could be well controlled to obtain a balance with the electrical performance of the p-type semiconductor,which is vital for achieving high-performance inverters.When the doping concentration of Sc is 10 at.%,the CMOS-like logic inverters exhibit a voltage gain larger than 80 and a wide noise margin(53%of the theoretical value).The inverters also respond well to the input signal with frequency up to 500 Hz.展开更多
Quinoidal small molecule semiconductors hold huge potential in ambipolar organic field-effect transistors(OFETs)and organic spintronic devices.Here,two quinoidal molecules with methylthio side chains were synthesized ...Quinoidal small molecule semiconductors hold huge potential in ambipolar organic field-effect transistors(OFETs)and organic spintronic devices.Here,two quinoidal molecules with methylthio side chains were synthesized to develop molecular semiconductors with high ambipolar mobility,designated QBDTS and QTBDTS.The theoretical calculation results reveal that QBDTS has a closed-shell structure while QTBDTS showed an open-shell structure with a biradical character(y0)of 0.46 and its magnetic properties were further investigated using electron paramagnetic resonance(EPR)and superconducting quantum interference device(SQUID)methods.The methyl side chains showed a large impact on the molecular orbital levels.The HOMO/LUMO levels of QBDTS and QTBDTS were measured to be-5.66/-4.56 and-5.27/-4.48 eV,respectively,which are favorable for ambipolar charge transport in OFETs.Importantly,the spin-coated QBDTS displayed hole and electron mobilities of 0.01 and 0.5 cm^(2)V^(-1)s^(-1)while QTBDTS showed a record high hole mobility of 1.8 cm^(2)V^(-1)s^(-1)and electron mobility of 0.3 cm^(2)V^(-1)s^(-1).Moreover,comparative studies of the thin film morphologies also manifested the beneficial influence of methyl side chains on film crystallinity and molecule orientation.These results strongly proved that methyl side chain engineering can be a simple but efficient strategy for modulating electronic properties and molecular stacking behaviors.This work also represents a big advancement for quinoidal molecular semiconductors in ambipolar OFET applications.展开更多
Mixed-dimensional composite structures using zero-dimensional(0D)quantum dots(QDs)and two-dimensional(2D)transition metal dichalcogenides(TMDs)materials are expected to attract great interest in optoelectronics due to...Mixed-dimensional composite structures using zero-dimensional(0D)quantum dots(QDs)and two-dimensional(2D)transition metal dichalcogenides(TMDs)materials are expected to attract great interest in optoelectronics due to the potential to generate new optical properties.Here,we report on the unique optical characteristics of a devices with mixed dimensional vertically stacked structures based on tungsten diselenide(WSe_(2))/CdSeS QDs monolayer/molybdenum disulfide(MoS_(2))(2D/0D/2D).Specifically,it exhibits an ambipolar photoresponse characteristic,with a negative photoresponse observed in the 400-600 nm wavelength range and a positive photoresponse appeared at 700 nm wavelength.It resulted in the high negative responsivity of up to 52.22 mA·W^(−1)under 400 nm,which is 163 times higher than that of the photodetector without CdSeS QDs.We also demonstrated the negative photoresponse,which could be due to increased carrier collision probability and non-radiative recombination.Device modeling and simulation reveal that Auger recombination among the types of non-radiative recombination is the main cause of negative photocurrent generation.Consequently,we discovered ambipolar photoresponse near a specific wavelength corresponding to the energy of quantum dots.Our study revealed interesting phenomenon in the mixed low-dimensional stacked structure and paved the way to exploit it for the development of innovative photodetection materials as well as for optoelectronic applications.展开更多
Single-component ambipolar polymers are highly desirable for organic electrochem-ical transistors(OECTs)and integration into complementary logic circuits with reduced process complexity.However,they often suffer from ...Single-component ambipolar polymers are highly desirable for organic electrochem-ical transistors(OECTs)and integration into complementary logic circuits with reduced process complexity.However,they often suffer from imbalanced p-type and n-type characteristics and/or stability issues.Herein,a novel single-component ambipolar polymer,namely,gIDT–BBT is reported based on indacenodithiophene(IDT)as the electron donor,benzobisthiadiazole(BBT)as the electron acceptor and oligo ethylene glycol(OEG)as the side chain.Benefitting from the extended backbone planarity and rigidity of IDT,pronounced electron-withdrawing capabil-ity of BBT,favored ionic transport from OEG together with vertical OECT device structure,a nearly balanced ambipolar OECT performance is achieved for gIDT–BBT,revealing a high transconductance of 155.05±1.58/27.28±0.92 mS,a high current on/off ratio>10^(6) and an excellent operational stability under both p-type and n-type operation conditions.With gIDT–BBT in hand,furthermore,vertically stacked complementary inverters are successfully fabricated to show a maximum voltage gain of 28 V V^(-1)(V_(IN)=0.9 V)and stable operation over 1000 switching cycles,and then used for efficient electrooculogram recording.This work provides a new approach for the development of ambipolar single-component organic mixed ionic–electronic conductors and establishes a foundation for the manufacture of high-performance ambipolar OECTs and associated complementary circuits.展开更多
Artificial synapses with full synapse-like functionalities are of crucial importance for the implementation of neuromorphic computing and bioinspired intelligent systems. In particular, the development of artificial s...Artificial synapses with full synapse-like functionalities are of crucial importance for the implementation of neuromorphic computing and bioinspired intelligent systems. In particular, the development of artificial synapses with the capability to emulate multiplexed neural transmission is highly desirable, but remains challenging. In this work, we proposed a hybrid ambipolar synaptic transistor that combines two-dimensional(2D) molybdenum disulfide(Mo S_(2)) sheet and crystalline one-dimensional(1D) poly(3-hexylthiophene-2,5-diyl) polymer nanowires(P3HT NWs) as dual excitatory channels. Essential synaptic functions, including excitatory postsynaptic current, paired-pulse facilitation, synaptic potentiation and depression, and dynamic filtering were emulated using the synaptic transistor. Benefitting from the dual excitatory channels of the synaptic transistor, the device achieved a fast switch between short-term and long-term memory by altering the charge carriers in the dual channels, i.e., electrons and holes. This emulated the multiplexed neural transmission of different excitatory neurotransmitters, e.g., dopamine and noradrenaline. The plasticity-switchable artificial synapse(PSAS) simulates the task-learning process of individuals under different motivations and the impact of success or failure on task learning and memory, which promises the potential to enable complex functionalities in future neuromorphic intelligent electronics.展开更多
Image sensors with an in-sensor computing architecture have shown great potential in meeting the energy-efficient requirements of emergent data-intensive applications,where images are processed within the photodiode a...Image sensors with an in-sensor computing architecture have shown great potential in meeting the energy-efficient requirements of emergent data-intensive applications,where images are processed within the photodiode arrays.It demands the composed photodiodes are reconfigurable,which are usually achieved by ambipolar two-dimensional(2D)semiconductors.To improve the ambipolar charges injection,here we report a top-gated field-effect transistor(FET)design that is of bottom van der Waals contact via transferring ambipolar 2D WSe_(2) onto Pd/Cr source/drain electrodes.The devices exhibit nearly negligible effective barrier heights for both holes and electrons based on thermionic emission mode,and show an almost balanced on/off ratio in the p-branch and n-branch.By replacing the top gate with two aligned semi-gates,the devices can effectively function as reconfigurable photodiodes.They can be switched between PIN and NIP configurations via controlling the two semi-gates,exhibiting good linearity in terms of short-circuit current(ISC)and incident light power density.The photodiode arrays are also demonstrated for in-sensor optoelectronic convolutional image processing,showing significant potential for in-sensor computing image processors.展开更多
Two-dimensional(2D)tribotronic devices have been successfully involved in electromechanical modulation for channel conductance and applied in intelligent sensing system,touch screen,and logic gates.Ambipolar transisto...Two-dimensional(2D)tribotronic devices have been successfully involved in electromechanical modulation for channel conductance and applied in intelligent sensing system,touch screen,and logic gates.Ambipolar transistors and corresponding complementary inverters based on one type of semiconductors are highly promising due to the facile fabrication process and readily tunable polarity.Here,we demonstrate an ambipolar tribotronic transistor of molybdenum ditelluride(MoTe_(2)),which shows typical ambipolar transport properties modulated by triboelectric potential.It is comprised of a MoTe_(2)transistor and a lateral sliding triboelectric nanogenerator(TENG).The induced triboelectric potential by Maxwell’s displacement current(a driving force for TENG)can readily modulate the transport properties of both electrons and holes in MoTe_(2)channel and effectively drive the transistor.High performance tribotronic properties have been achieved,including low cutoff current below 1 pA·μm^(−1)and high current on/off ratio of~103 for holes and electrons dominated transports.The working mechanism on how to achieve tribotronic ambipolarity is discussed in detail.A complementary tribotronic inverter based on single flake of MoTe_(2)is also demonstrated with low power consumption and high stability.This work presents an active approach to efficiently modulate semiconductor devices and logic circuits based on 2D materials through external mechanical signal,which has great potential in human–machine interaction,intelligent sensor,and other wearable devices.展开更多
The key building blocks,tetrachlorinated terrylene diimides and the targeted sila-annulated terrylene diimides(Si-TDIs and 2Si-TDIs)were synthesized for the first time.Single-crystal analysis verified the almost plana...The key building blocks,tetrachlorinated terrylene diimides and the targeted sila-annulated terrylene diimides(Si-TDIs and 2Si-TDIs)were synthesized for the first time.Single-crystal analysis verified the almost planar molecular configurations of both Si-TDIs and 2Si-TDIs.They exhibited intriguing optical properties including red-shifted absorption and near-infrared emission properties with excellent fluorescence quantum yields,as well as precisely controlled HOMO/LUMO energy levels by Si-heteroannulation.The single-crystal organic field-effect transistors based on 2Si-TDI 5a featuring long and branched alkyl chains demonstrated well-balanced ambipolar transporting properties with electron/hole mobilities of 0.10/0.18 cm2 V^(−1)s^(−1).展开更多
In this study,a family of three benzodifurandione-baseddonor–acceptor(D–A)copolymers,namelypoly[3,7-bis((E)-1-(4-octadecyldocosyl)-2-oxo-6-yl-indolin-3-ylidene)-3,7-dihydrobenzo[1,2-b:4,5-b′]difuran-2,6-dionealt-(E...In this study,a family of three benzodifurandione-baseddonor–acceptor(D–A)copolymers,namelypoly[3,7-bis((E)-1-(4-octadecyldocosyl)-2-oxo-6-yl-indolin-3-ylidene)-3,7-dihydrobenzo[1,2-b:4,5-b′]difuran-2,6-dionealt-(E)-1,2-di(2,2′-bithiophen-5-yl)ethene](PBDO-DTE),poly[3,7-bis((E)-7-fluoro-1-(4-octadecyldocosyl)-2-oxo-6-yl-indolin-3-ylidene)-3,7-dihydrobenzo[1,2-b:4,5-b′]difuran-2,6-dione-alt-(E)-1,2-di(2,2′-bithiophen-5-yl)ethene](PFBDO-DTE),and poly[(3E,7E)-3,7-bis(1-(4-octadecyldocosyl)-2-oxo-6-yl-1,2-dihydro-3Hpyrrolo[2,3-b]pyridin-3-ylidene)-3,7-dihydrobenzo[1,2-b:4,5-b′]difuran-2,6-dione-alt-(E)-1,2-di(2,2′-bithiophen-5-yl)ethene](PNBDO-DTE),was designed and synthesized by employing aldol polycondensation reactions between benzodifurandione and bisindolin-2-ones in high yields.Further incorporation of fluorine or sp2-hybridized nitrogen atoms on the bisindolin-2-one unit induced S…F or S…N nonbonding interactions-locked polymeric conjugated backbones for PFBDO-DTE and PNBDO-DTE,respectively.Ultraviolet photoelectron spectroscopy and inverse photoemission spectroscopy measurements revealed that the two copolymers have lower frontier molecular orbitals than that of PBDO-DTE.Atomic force microscopy and two-dimensional grazing-incidence wide-angle X-ray scattering investigations indicated the PNBDO-DTE copolymer could form more ordered molecular aggregation in the solid state than PBDO-DTE and PFBDO-DTE copolymers.We fabricated thin film transistors based on these copolymers on plastic polyethylene terephthalate substrates,and they all showed ambipolar charge transport characteristics.Among them,the PNBDO-DTE-based devices afforded optimal charge transport characteristics with high hole and electron mobilities of 5.16 and 1.33cm^(2)V^(−1)s^(−1),respectively.Our study highlights that aldol polycondensation would be an extremely useful protocol in constructing high-performance polymer semiconductors.展开更多
Two-dimensional materials have been demonstrated as promising toolboxes for optoelectronics.Transition metal carbides and nitrides(MXenes),members of an emerging family of two-dimensional materials,have drawn extensiv...Two-dimensional materials have been demonstrated as promising toolboxes for optoelectronics.Transition metal carbides and nitrides(MXenes),members of an emerging family of two-dimensional materials,have drawn extensive attention in optoelectronics owing to their excellent conductivity and tunable electronic properties.Herein,a photodetector based on the two-dimensional van der Waals heterostructure of Ti_(3)C_(2)T_(x)MXene and a MoS_(2)monolayer was constructed to observe the ambipolar photoresponse,which showed a positive photoresponse in the visible spectrum(500-700 nm)and a negative photoresponse at longer wavelengths(700-800 nm).The device exhibited a high negative responsivity of 1.9 A/W and a detectivity of 2.1×10^(10)Jones under 750 nm light illumination.Detailed experiments demonstrate that the negative photoresponse arises from the heterostructureinduced trap energy level,which confines the excited photoelectrons and leads to an inverse current.This work demonstrates a unique optoelectronic phenomenon in MoS_(2)/MXene heterostructures and provides valuable insights into the development of new photodetection materials.展开更多
High sensitive chemical sensors towards NO2 and NH3 based on the self-assembled nanostructures of the heteroleptic and homoleptic bis(phthalocyaninato) europium complexes with octanaphthoxy phthalocyaninato ligands ...High sensitive chemical sensors towards NO2 and NH3 based on the self-assembled nanostructures of the heteroleptic and homoleptic bis(phthalocyaninato) europium complexes with octanaphthoxy phthalocyaninato ligands named Eu(Pc)[Pc(ONh)8] (1) and Eu[Pc(ONh)8]2 (2) [Pc = unsubstituted phthalocyaninate; Pc(ONh)8 = 2,3,9,10,16,17,23,24-octanaphthoxy phthalocyaninate] have been developed. The good conductivity, high crystal- linity and large specific surface area for the self-assemblies of 1 render it excellent sensing property for either electron-accepting gas NO2 in 50--250 ppb range or electron-donating gas NH3 in 2.5--12.5 ppm range due to the optimized molecular packing in the uniform-sized nanopartieles depending on the effective intermolecular interaction between double-decker molecules, among the best results of phthalocyanine-based chemical sensors for detection of NO2 and NH3 at room temperature. Interestingly, self-assemblies of I exhibited n-type response to NO2 and p-type response to NH3, which is the first example of ambipolar charge-transporting gas sensors fabricated from single- component organic semiconductors. However, the self-assemblies of 2 with sixteen bulky naphtboxy groups at the periphery of two Pc rings only present an n-type response to strong oxidant gas NO2 in a relatively high concentration of 0.5 - 1.5 ppm, while are insensitive to weak reducing gas NH3 due to the existence of great steric hindrance from bulky naphthoxy groups and more traps and/or defects in self-assemblies.展开更多
In this paper,we report the design,synthesis and semiconducting behavior of two conjugated D-A polymers BPDDTE and BPDBDTE which entail BPD,a Pechmann dye framework,as electron accepting moieties and(E)-1,2-di(thiophe...In this paper,we report the design,synthesis and semiconducting behavior of two conjugated D-A polymers BPDDTE and BPDBDTE which entail BPD,a Pechmann dye framework,as electron accepting moieties and(E)-1,2-di(thiophen-2-yl)ethane with and without alkyl chains as electron donating moieties.They both show very narrow bandgaps below 1.3 eV.Based on the characterization of the field-effect transistors,thin film of BPDDT exhibits ambipolar semiconducting properties with hole and electron mobilities reaching 0.245 and 0.095 cm^(2)•V^(−1)•s^(−1),respectively,after thermal annealing.Similarly,BPDBDTE with more alkylchains shows ambipolar semiconducting behavior with hole mobility and electron mobilities reaching 0.109 and 0.081 cm^(2)•V^(−1)•s^(−1).Furthermore,BPDBDTE shows good solubilities in several common organic solvents and thus is easily solution-processible.Thus,BPDBDTE is potentially processible with inkjet printing and roll-to-roll printing techniques.展开更多
Conjugated polymers with well-balanced ambipolar charge transport is essential for organic circuits at low cost and large area with simplified fabrication techniques.Aiming at this point,herein,a novel asymmetric thio...Conjugated polymers with well-balanced ambipolar charge transport is essential for organic circuits at low cost and large area with simplified fabrication techniques.Aiming at this point,herein,a novel asymmetric thiophene/pyridine-flanked diketopyrrolopyrrole-based copolymer(PPyTDPP-2FBT)is designed and synthesized.Due to the effect of incorporating F atoms on molecular energy alignment and conjugation conformation,the PPyTDPP-2FBT copolymer exhibits typical V-shaped ambipolar field-effect transfer characteristics with well-balanced hole and electron mobilities of 0.64 and 0.46 cm^(2)V^(−1)s^(−1),respectively.Furthermore,organic digital and analog circuits such as inverters and frequency doublers are successfully constructed based on solution-processed films of the PPyTDPP-2FBT copolymers which show a typical circuit operating mode with a high gain of 133 due to the well-balanced electrical properties.In addition,PPyTDPP-2FBT-based devices also demonstrate good stability and batch repeatability,suggesting their great potential applications in organic integrated electronic circuits.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.62274037)the National Key Research and Development Program of China (Grant No.2018YFA0703703)+1 种基金the Ministry of Science and Technology of China (Grant No.2018YFE0118300)the State Key Laboratory of ASIC&System (Grant No.2021MS003)。
文摘In these days,the increasing massive data are being produced and demanded to be processed with the rapid growth of information technology.It is difficult to rely solely on the shrinking of semiconductor devices and scale-up of the integrated circuits(ICs)again in the foreseeable future.Exploring new materials,new-principle semiconductor devices and new computing architectures is becoming an urgent topic in this field.Ambipolar two-dimensional(2D)semiconductors,possessing excellent electrostatic field controllability and flexibly modulated major charge carriers,offer a possibility to construct reconfigurable devices and enable the ICs with new functions,showing great potential in computing capacity,energy efficiency,time delay and cost.This review focuses on the recent significant advancements in reconfigurable electronic and optoelectronic devices of ambipolar 2D semiconductors,and demonstrates their potential approach towards ICs,like reconfigurable circuits and neuromorphic chips.It is expected to help readers understand the device design principle of ambipolar 2D semiconductors,and push forward exploring more new-principle devices and new-architecture computing circuits,and even their product applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52177185 and 62174055)。
文摘Dual-metal gate and gate–drain underlap designs are introduced to reduce the ambipolar current of the device based on the C-shaped pocket TFET(CSP-TFET).The effects of gate work function and gate–drain underlap length on the DC characteristics and analog/RF performance of CSP-TFET devices,such as the on-state current(I_(on)),ambipolar current(I_(amb)),transconductance(g_(m)),cut-off frequency(f_(T))and gain–bandwidth product(GBP),are analyzed and compared in this work.Also,a combination of both the dual-metal gate and gate–drain underlap designs has been proposed for the C-shaped pocket dual metal underlap TFET(CSP-DMUN-TFET),which contains a C-shaped pocket area that significantly increases the on-state current of the device;this combination design substantially reduces the ambipolar current.The results show that the CSP-DMUN-TFET demonstrates an excellent performance,including high I_(on)(9.03×10^(-4)A/μm),high I_(on)/I_(off)(~10^(11)),low SS_(avg)(~13 mV/dec),and low I_(amb)(2.15×10^(-17)A/μm).The CSP-DMUN-TFET has the capability to fully suppress ambipolar currents while maintaining high on-state currents,making it a potential replacement in the next generation of semiconductor devices.
文摘In the present paper, based on the conservation law of mass and momentum for ion and electron, the distribution of velocity, density of ions and electrons along radial direction are solved numerically. Furthermore, the comparison between MHD properties of ambipolar and qua- si- ambipolar diffusion is made. The numerical calculation is carried out for argon plasma. The results show that the ion density, ratio of ion and electron velocity at the cathode sheath boundary surface in- crease with the intensity of magnetic induction, meanwhile, the distance between sheaths decreases as well as the radial velocity of ion and electron at the anode sheath boundary. The ion density varies in accord with experiment qualitatively. All parameters mentioned above are not sensitive to magnetic field in ambipolar diffusion.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60676033 and 60276026)the Natural Science Foundation of Gansu Province,China (Grant No ZS031-A25-012-G)‘Qing Lan’ Talent Engineering Funds from Lanzhou Jiaotong University,China (Grant No QL-08-18A)
文摘Fabrication of ambipolar organic field-effect transistors (OFETs) is essential for the achievement of an organic complementary logic circuit. Ambipolar transports in OFETs with heterojunction structures are realized.We select pentacene as a P-type material and N,N'-bis(4-trifluoromethylben-zyl)perylene-3,4,9,10-tetracarboxylic diimide (PTCDI-TFB) as a n-type material in the active layer of the OFETs.The field-effect transistor shows highly air-stable ambipolar characteristics with a field-effect hole mobility of 0.18 cm^2/(V·s) and field-effect electron mobility of 0.031 cm^2/(V·s).Furthermore the mobility only slightly decreases after being exposed to air and remains stable even for exposure to air for more than 60 days.The high electron affinity of PTCDI-TFB and the octadecyltrichlorosilane (OTS) self-assembly monolayer between the SiO2 gate dielectric and the organic active layer result in the observed air-stable characteristics of OFETs with high mobility.The results demonstrate that using the OTS as a modified gate insulator layer and using high electron affinity semiconductor materials are two effective methods to fabricate OFETs with air-stable characteristics and high mobility.
基金Project supported by the University Natural Science Research Key Project of Anhui Province,China(Grant No.KJ2017A502)the Introduced Talent Project of Anhui Science and Technology University,China(Grant No.DQYJ201603)+1 种基金the Excellent Talents Supporting Project of Colleges and Universities,China(Grant No.gxyq2018048)the Innovation and Entrepreneurship Training Program for College Students,China(Grant No.2018S10879052)
文摘A tunnel field-effect transistor(TFET) is proposed by combining various advantages together, such as non-uniform gate-oxide layer, hetero-gate-dielectric(HGD), and dual-material control-gate(DMCG) technology. The effects of the length of non-uniform gate-oxide layer and dual-material control-gate on the on-state, off-state, and ambipolar currents are investigated. In addition, radio-frequency performance is studied in terms of gain bandwidth product, cut-off frequency,transit time, and transconductance frequency product. Moreover, the length of non-uniform gate-oxide layer and dualmaterial control-gate are optimized to improve the on-off current ratio and radio-frequency performances as well as the suppression of ambipolar current. All results demonstrate that the proposed device not only suppresses ambipolar current but also improves radio-frequency performance compared with the conventional DMCG TFET, which makes the proposed device a better application prospect in the advanced integrated circuits.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61306116 and 61472322)
文摘A new T-shaped tunnel field-effect transistor(TTFET) with gate dielectric spacer(GDS) structure is proposed in this paper. To further studied the effects of GDS structure on the TTFET, detailed device characteristics such as current-voltage relationships, energy band diagrams, band-to-band tunneling(BTBT) rate and the magnitude of the electric field are investigated by using TCAD simulation. It is found that compared with conventional TTFET and TTFET with gate-drain overlap(GDO) structure, GDS-TTFET not only has the minimum ambipolar current but also can suppress the ambipolar current under a more extensive bias range. Furthermore, the analog/RF performances of GDS-TTFET are also investigated in terms of transconductance, gate-source capacitance, gate-drain capacitance, cutoff frequency, and gain bandwidth production. By inserting a low-κ spacer layer between the gate electrode and the gate dielectric, the GDS structure can effectively reduce parasitic capacitances between the gate and the source/drain, which leads to better performance in term of cutoff frequency and gain bandwidth production. Finally, the thickness of the gate dielectric spacer is optimized for better ambipolar current suppression and improved analog/RF performance.
文摘A mathematical model and experimental analysis of the impact of oxide thickness on the ambipolar conduction in Schottky Barrier Carbon Nanotubes(CNTs)Field Effect Transistor(SB CNTFETs)is presented.Suppression of ambipolar conduction in SB CNTFETs is imperative in order to establish them as the future of IC technology.The ambipolar nature of SB CNTFETs leads to a great amount of leakage current.Employing a gate oxide dielectric of thickness,tox^50 nm suppresses the ambipolar behavior.In an SB CNTFET,it is the electric field at the source/drain contacts that control the conductance and the band bending length at the contacts is defined by tox.Therefore,tox is the prime parameter that influences the width of the Schottky barrier and the current in the subthreshold region.Due to the wide SB,there is a loss in on-current due to tunneling,but the current due to thermionic emission is increased by employing a high-κdielectric such as Zirconium dioxide(ZrO2).This work proposes an approach to suppress ambipolar behavior in SB CNTFETs without decreasing the on current.The thickness and dielectric constant of the gate oxide are optimized using the particle swarm optimization(PSO)algorithm to achieve suppression of ambipolar conduction without any loss in on-current.The proposed SB CNTFET was modeled using Verilog-A.Experimental demonstration of the suppression of ambipolar property is also presented.Two SB CNTFETs are fabricated using high-κdielectric such as ZrO2 with different thickness.A device with thin(~5 nm)gate oxide and another device with thick(~50 nm)gate oxide were fabricated.From the experimental results,it is observed that the device with the thin gate oxide exhibited ambipolar characteristics and the device with the thick gate oxide did not exhibit ambipolar characteristics.The increase in thickness,tox,ensures suppression of ambipolar behavior.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61574003 and 61774010)Shenzhen Municipal Scientific Program,China(Grant Nos.GGFW20170728163447038 and JCYJ20180504165449640).
文摘This work reports on the integration of organic and inorganic semiconductors as heterojunction active layers for high-performance ambipolar transistors and complementary metal-oxide-semiconductor(CMOS)-like inverters.Pentacene is employed as a p-type organic semiconductor for its stable electrical performance,while the solution-processed scandium(Sc)substituted indium oxide(ScInO)is employed as an n-type inorganic semiconductor.It is observed that by regulating the doping concentration of Sc,the electrical performance of the n-type semiconductor could be well controlled to obtain a balance with the electrical performance of the p-type semiconductor,which is vital for achieving high-performance inverters.When the doping concentration of Sc is 10 at.%,the CMOS-like logic inverters exhibit a voltage gain larger than 80 and a wide noise margin(53%of the theoretical value).The inverters also respond well to the input signal with frequency up to 500 Hz.
基金supported by the National Natural Science Foundation of China(21801201,51773160,21975194,22175134)the Research Fund for Distinguished Young Scholars of Hubei Province(2019CFA042)。
文摘Quinoidal small molecule semiconductors hold huge potential in ambipolar organic field-effect transistors(OFETs)and organic spintronic devices.Here,two quinoidal molecules with methylthio side chains were synthesized to develop molecular semiconductors with high ambipolar mobility,designated QBDTS and QTBDTS.The theoretical calculation results reveal that QBDTS has a closed-shell structure while QTBDTS showed an open-shell structure with a biradical character(y0)of 0.46 and its magnetic properties were further investigated using electron paramagnetic resonance(EPR)and superconducting quantum interference device(SQUID)methods.The methyl side chains showed a large impact on the molecular orbital levels.The HOMO/LUMO levels of QBDTS and QTBDTS were measured to be-5.66/-4.56 and-5.27/-4.48 eV,respectively,which are favorable for ambipolar charge transport in OFETs.Importantly,the spin-coated QBDTS displayed hole and electron mobilities of 0.01 and 0.5 cm^(2)V^(-1)s^(-1)while QTBDTS showed a record high hole mobility of 1.8 cm^(2)V^(-1)s^(-1)and electron mobility of 0.3 cm^(2)V^(-1)s^(-1).Moreover,comparative studies of the thin film morphologies also manifested the beneficial influence of methyl side chains on film crystallinity and molecule orientation.These results strongly proved that methyl side chain engineering can be a simple but efficient strategy for modulating electronic properties and molecular stacking behaviors.This work also represents a big advancement for quinoidal molecular semiconductors in ambipolar OFET applications.
基金the financial support from the KIST Institution Program(No.2E32634)Basic Science Research Program through the National Research Foundation of Korea(NRF)grant funded by the Korea government(Ministry of Science and ICT)(Nos.NRF-2017R1A2B3002307 and NRF-2016M3A7B4900135)+1 种基金Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.NRF-2020R1A6A3A01099388)the National R&D Program through the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT(Nos.NRF-2022M3H4A1A04074153 and RS-2023-00239634).
文摘Mixed-dimensional composite structures using zero-dimensional(0D)quantum dots(QDs)and two-dimensional(2D)transition metal dichalcogenides(TMDs)materials are expected to attract great interest in optoelectronics due to the potential to generate new optical properties.Here,we report on the unique optical characteristics of a devices with mixed dimensional vertically stacked structures based on tungsten diselenide(WSe_(2))/CdSeS QDs monolayer/molybdenum disulfide(MoS_(2))(2D/0D/2D).Specifically,it exhibits an ambipolar photoresponse characteristic,with a negative photoresponse observed in the 400-600 nm wavelength range and a positive photoresponse appeared at 700 nm wavelength.It resulted in the high negative responsivity of up to 52.22 mA·W^(−1)under 400 nm,which is 163 times higher than that of the photodetector without CdSeS QDs.We also demonstrated the negative photoresponse,which could be due to increased carrier collision probability and non-radiative recombination.Device modeling and simulation reveal that Auger recombination among the types of non-radiative recombination is the main cause of negative photocurrent generation.Consequently,we discovered ambipolar photoresponse near a specific wavelength corresponding to the energy of quantum dots.Our study revealed interesting phenomenon in the mixed low-dimensional stacked structure and paved the way to exploit it for the development of innovative photodetection materials as well as for optoelectronic applications.
基金Sichuan Science and Technology Program,Grant/Award Number:2023ZYD0161Chengdu Science and Technology Bureau,Grant/Award Number:2023-YF06-00028-HZ+5 种基金National Natural Science Foundation of China,Grant/Award Numbers:92163132,52263019,52273316,62273073Yunnan Fundamental Research Project,Grant/Award Number:202301AT070313Yunling Scholar Project of“Yunnan Revitalization Talent Support Program”National Key Research and Development Program of China,Grant/Award Numbers:2022YFE0134800,2023YFC2411800Aeronautical Science Foundation of China,Grant/Award Number:20230024080002Yunnan Provincial Department of Education Science Research Fund Graduate Program,Grant/Award Number:2023Y0236。
文摘Single-component ambipolar polymers are highly desirable for organic electrochem-ical transistors(OECTs)and integration into complementary logic circuits with reduced process complexity.However,they often suffer from imbalanced p-type and n-type characteristics and/or stability issues.Herein,a novel single-component ambipolar polymer,namely,gIDT–BBT is reported based on indacenodithiophene(IDT)as the electron donor,benzobisthiadiazole(BBT)as the electron acceptor and oligo ethylene glycol(OEG)as the side chain.Benefitting from the extended backbone planarity and rigidity of IDT,pronounced electron-withdrawing capabil-ity of BBT,favored ionic transport from OEG together with vertical OECT device structure,a nearly balanced ambipolar OECT performance is achieved for gIDT–BBT,revealing a high transconductance of 155.05±1.58/27.28±0.92 mS,a high current on/off ratio>10^(6) and an excellent operational stability under both p-type and n-type operation conditions.With gIDT–BBT in hand,furthermore,vertically stacked complementary inverters are successfully fabricated to show a maximum voltage gain of 28 V V^(-1)(V_(IN)=0.9 V)and stable operation over 1000 switching cycles,and then used for efficient electrooculogram recording.This work provides a new approach for the development of ambipolar single-component organic mixed ionic–electronic conductors and establishes a foundation for the manufacture of high-performance ambipolar OECTs and associated complementary circuits.
基金supported by the National Science Fund for Distinguished Young Scholars of China (No. T2125005)the Tianjin Science Foundation for Distinguished Young Scholars (No. 19JCJQJC61000)the Shenzhen Science and Technology Project (No. JCYJ20210324121002008)。
文摘Artificial synapses with full synapse-like functionalities are of crucial importance for the implementation of neuromorphic computing and bioinspired intelligent systems. In particular, the development of artificial synapses with the capability to emulate multiplexed neural transmission is highly desirable, but remains challenging. In this work, we proposed a hybrid ambipolar synaptic transistor that combines two-dimensional(2D) molybdenum disulfide(Mo S_(2)) sheet and crystalline one-dimensional(1D) poly(3-hexylthiophene-2,5-diyl) polymer nanowires(P3HT NWs) as dual excitatory channels. Essential synaptic functions, including excitatory postsynaptic current, paired-pulse facilitation, synaptic potentiation and depression, and dynamic filtering were emulated using the synaptic transistor. Benefitting from the dual excitatory channels of the synaptic transistor, the device achieved a fast switch between short-term and long-term memory by altering the charge carriers in the dual channels, i.e., electrons and holes. This emulated the multiplexed neural transmission of different excitatory neurotransmitters, e.g., dopamine and noradrenaline. The plasticity-switchable artificial synapse(PSAS) simulates the task-learning process of individuals under different motivations and the impact of success or failure on task learning and memory, which promises the potential to enable complex functionalities in future neuromorphic intelligent electronics.
基金supported by the National Natural Science Foundation of China(No.62274037)the National Key Research and Development Program of China(No.2018YFA0703703)+1 种基金the Ministry of Science and Technology of China(No.2018YFE0118300)State Key Laboratory of ASIC&System(No.2021MS003).
文摘Image sensors with an in-sensor computing architecture have shown great potential in meeting the energy-efficient requirements of emergent data-intensive applications,where images are processed within the photodiode arrays.It demands the composed photodiodes are reconfigurable,which are usually achieved by ambipolar two-dimensional(2D)semiconductors.To improve the ambipolar charges injection,here we report a top-gated field-effect transistor(FET)design that is of bottom van der Waals contact via transferring ambipolar 2D WSe_(2) onto Pd/Cr source/drain electrodes.The devices exhibit nearly negligible effective barrier heights for both holes and electrons based on thermionic emission mode,and show an almost balanced on/off ratio in the p-branch and n-branch.By replacing the top gate with two aligned semi-gates,the devices can effectively function as reconfigurable photodiodes.They can be switched between PIN and NIP configurations via controlling the two semi-gates,exhibiting good linearity in terms of short-circuit current(ISC)and incident light power density.The photodiode arrays are also demonstrated for in-sensor optoelectronic convolutional image processing,showing significant potential for in-sensor computing image processors.
基金financially supported by the National Key Research and Development Program of China(No.2021YFB3200304)the National Natural Science Foundation of China(No.52073031)+2 种基金the Beijing Nova Program(Nos.Z191100001119047 and Z211100002121148)the Fundamental Research Funds for the Central Universities(No.E0EG6801X2)the“Hundred Talents Program”of the Chinese Academy of Sciences.
文摘Two-dimensional(2D)tribotronic devices have been successfully involved in electromechanical modulation for channel conductance and applied in intelligent sensing system,touch screen,and logic gates.Ambipolar transistors and corresponding complementary inverters based on one type of semiconductors are highly promising due to the facile fabrication process and readily tunable polarity.Here,we demonstrate an ambipolar tribotronic transistor of molybdenum ditelluride(MoTe_(2)),which shows typical ambipolar transport properties modulated by triboelectric potential.It is comprised of a MoTe_(2)transistor and a lateral sliding triboelectric nanogenerator(TENG).The induced triboelectric potential by Maxwell’s displacement current(a driving force for TENG)can readily modulate the transport properties of both electrons and holes in MoTe_(2)channel and effectively drive the transistor.High performance tribotronic properties have been achieved,including low cutoff current below 1 pA·μm^(−1)and high current on/off ratio of~103 for holes and electrons dominated transports.The working mechanism on how to achieve tribotronic ambipolarity is discussed in detail.A complementary tribotronic inverter based on single flake of MoTe_(2)is also demonstrated with low power consumption and high stability.This work presents an active approach to efficiently modulate semiconductor devices and logic circuits based on 2D materials through external mechanical signal,which has great potential in human–machine interaction,intelligent sensor,and other wearable devices.
基金This work was financially supported by the National Natural Science Foundation of China(NSFC,Nos.21901138,21790361 and 22122503)the Shandong Provincial Natural Science Foundation(No.ZR2019ZD50)China Fundamental Research Funds for the Central Universities(No.2-9-2020-041).
文摘The key building blocks,tetrachlorinated terrylene diimides and the targeted sila-annulated terrylene diimides(Si-TDIs and 2Si-TDIs)were synthesized for the first time.Single-crystal analysis verified the almost planar molecular configurations of both Si-TDIs and 2Si-TDIs.They exhibited intriguing optical properties including red-shifted absorption and near-infrared emission properties with excellent fluorescence quantum yields,as well as precisely controlled HOMO/LUMO energy levels by Si-heteroannulation.The single-crystal organic field-effect transistors based on 2Si-TDI 5a featuring long and branched alkyl chains demonstrated well-balanced ambipolar transporting properties with electron/hole mobilities of 0.10/0.18 cm2 V^(−1)s^(−1).
基金made possible as a result of a generous grant from the Beijing Municipal Natural Science Foundation(grant no.2212054)the National Natural Science Foundation of China(grants nos.22075294,22275194,22175021,22021002)Beijing National Laboratory for Molecular Sciences(grant no.BNLMSCXXM-202101).
文摘In this study,a family of three benzodifurandione-baseddonor–acceptor(D–A)copolymers,namelypoly[3,7-bis((E)-1-(4-octadecyldocosyl)-2-oxo-6-yl-indolin-3-ylidene)-3,7-dihydrobenzo[1,2-b:4,5-b′]difuran-2,6-dionealt-(E)-1,2-di(2,2′-bithiophen-5-yl)ethene](PBDO-DTE),poly[3,7-bis((E)-7-fluoro-1-(4-octadecyldocosyl)-2-oxo-6-yl-indolin-3-ylidene)-3,7-dihydrobenzo[1,2-b:4,5-b′]difuran-2,6-dione-alt-(E)-1,2-di(2,2′-bithiophen-5-yl)ethene](PFBDO-DTE),and poly[(3E,7E)-3,7-bis(1-(4-octadecyldocosyl)-2-oxo-6-yl-1,2-dihydro-3Hpyrrolo[2,3-b]pyridin-3-ylidene)-3,7-dihydrobenzo[1,2-b:4,5-b′]difuran-2,6-dione-alt-(E)-1,2-di(2,2′-bithiophen-5-yl)ethene](PNBDO-DTE),was designed and synthesized by employing aldol polycondensation reactions between benzodifurandione and bisindolin-2-ones in high yields.Further incorporation of fluorine or sp2-hybridized nitrogen atoms on the bisindolin-2-one unit induced S…F or S…N nonbonding interactions-locked polymeric conjugated backbones for PFBDO-DTE and PNBDO-DTE,respectively.Ultraviolet photoelectron spectroscopy and inverse photoemission spectroscopy measurements revealed that the two copolymers have lower frontier molecular orbitals than that of PBDO-DTE.Atomic force microscopy and two-dimensional grazing-incidence wide-angle X-ray scattering investigations indicated the PNBDO-DTE copolymer could form more ordered molecular aggregation in the solid state than PBDO-DTE and PFBDO-DTE copolymers.We fabricated thin film transistors based on these copolymers on plastic polyethylene terephthalate substrates,and they all showed ambipolar charge transport characteristics.Among them,the PNBDO-DTE-based devices afforded optimal charge transport characteristics with high hole and electron mobilities of 5.16 and 1.33cm^(2)V^(−1)s^(−1),respectively.Our study highlights that aldol polycondensation would be an extremely useful protocol in constructing high-performance polymer semiconductors.
基金the support from the National Natural Science Foundation of China(Nos.21971172 and 21671141)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions for Optical Engineering in Soochow University,and Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering in Changzhou University(No.RC-ICRS/15-16/02(HKBU)).
文摘Two-dimensional materials have been demonstrated as promising toolboxes for optoelectronics.Transition metal carbides and nitrides(MXenes),members of an emerging family of two-dimensional materials,have drawn extensive attention in optoelectronics owing to their excellent conductivity and tunable electronic properties.Herein,a photodetector based on the two-dimensional van der Waals heterostructure of Ti_(3)C_(2)T_(x)MXene and a MoS_(2)monolayer was constructed to observe the ambipolar photoresponse,which showed a positive photoresponse in the visible spectrum(500-700 nm)and a negative photoresponse at longer wavelengths(700-800 nm).The device exhibited a high negative responsivity of 1.9 A/W and a detectivity of 2.1×10^(10)Jones under 750 nm light illumination.Detailed experiments demonstrate that the negative photoresponse arises from the heterostructureinduced trap energy level,which confines the excited photoelectrons and leads to an inverse current.This work demonstrates a unique optoelectronic phenomenon in MoS_(2)/MXene heterostructures and provides valuable insights into the development of new photodetection materials.
基金We are thankful for financial support from the National Natural Science Foundation of China (Nos. 21371073 and 21290174), the National Key Basic Research Program of China (Nos. 2013CB933402 and 2012CB224801), the Fundamental Research Funds for the Central Universities (No. 16CX06022A) and Research Fund for Introduced Talents of China University of Petroleum (No.Y 1510051).
文摘High sensitive chemical sensors towards NO2 and NH3 based on the self-assembled nanostructures of the heteroleptic and homoleptic bis(phthalocyaninato) europium complexes with octanaphthoxy phthalocyaninato ligands named Eu(Pc)[Pc(ONh)8] (1) and Eu[Pc(ONh)8]2 (2) [Pc = unsubstituted phthalocyaninate; Pc(ONh)8 = 2,3,9,10,16,17,23,24-octanaphthoxy phthalocyaninate] have been developed. The good conductivity, high crystal- linity and large specific surface area for the self-assemblies of 1 render it excellent sensing property for either electron-accepting gas NO2 in 50--250 ppb range or electron-donating gas NH3 in 2.5--12.5 ppm range due to the optimized molecular packing in the uniform-sized nanopartieles depending on the effective intermolecular interaction between double-decker molecules, among the best results of phthalocyanine-based chemical sensors for detection of NO2 and NH3 at room temperature. Interestingly, self-assemblies of I exhibited n-type response to NO2 and p-type response to NH3, which is the first example of ambipolar charge-transporting gas sensors fabricated from single- component organic semiconductors. However, the self-assemblies of 2 with sixteen bulky naphtboxy groups at the periphery of two Pc rings only present an n-type response to strong oxidant gas NO2 in a relatively high concentration of 0.5 - 1.5 ppm, while are insensitive to weak reducing gas NH3 due to the existence of great steric hindrance from bulky naphthoxy groups and more traps and/or defects in self-assemblies.
基金The present research was financially supported by Chinese Academy of Sciences,NSFC(No.21372226)and State Key Basic Research Program.
文摘In this paper,we report the design,synthesis and semiconducting behavior of two conjugated D-A polymers BPDDTE and BPDBDTE which entail BPD,a Pechmann dye framework,as electron accepting moieties and(E)-1,2-di(thiophen-2-yl)ethane with and without alkyl chains as electron donating moieties.They both show very narrow bandgaps below 1.3 eV.Based on the characterization of the field-effect transistors,thin film of BPDDT exhibits ambipolar semiconducting properties with hole and electron mobilities reaching 0.245 and 0.095 cm^(2)•V^(−1)•s^(−1),respectively,after thermal annealing.Similarly,BPDBDTE with more alkylchains shows ambipolar semiconducting behavior with hole mobility and electron mobilities reaching 0.109 and 0.081 cm^(2)•V^(−1)•s^(−1).Furthermore,BPDBDTE shows good solubilities in several common organic solvents and thus is easily solution-processible.Thus,BPDBDTE is potentially processible with inkjet printing and roll-to-roll printing techniques.
基金This work is financially supported by the Ministry of Science and Technology of China(2018YFA0703200,2017YFA0204503)the National Natural Science Foundation of China(91833306,61890943,51725304,22021002)Beijing National Laboratory for Molecular Sciences(BNLMS-CXXM-202012),the Youth Innovation Promotion Association of the Chinese Academy of Sciences,and the National Program for Support of Top-notch Young Professionals.
文摘Conjugated polymers with well-balanced ambipolar charge transport is essential for organic circuits at low cost and large area with simplified fabrication techniques.Aiming at this point,herein,a novel asymmetric thiophene/pyridine-flanked diketopyrrolopyrrole-based copolymer(PPyTDPP-2FBT)is designed and synthesized.Due to the effect of incorporating F atoms on molecular energy alignment and conjugation conformation,the PPyTDPP-2FBT copolymer exhibits typical V-shaped ambipolar field-effect transfer characteristics with well-balanced hole and electron mobilities of 0.64 and 0.46 cm^(2)V^(−1)s^(−1),respectively.Furthermore,organic digital and analog circuits such as inverters and frequency doublers are successfully constructed based on solution-processed films of the PPyTDPP-2FBT copolymers which show a typical circuit operating mode with a high gain of 133 due to the well-balanced electrical properties.In addition,PPyTDPP-2FBT-based devices also demonstrate good stability and batch repeatability,suggesting their great potential applications in organic integrated electronic circuits.