Designing simple non-fused terthiophene-based electron acceptors for efficient organic solar cells

Low-cost photovoltaic materials are essential for realizing large-scale commercial applications of organic solar cells(OSCs).However,highly efficient OSCs based on low-cost photovoltaic materials are scarce due to a deficiency in understanding the structure-property relationship.Herein,we investigated two low-cost terthiophene-based electron acceptors,namely,3TC8 and 3TEH,with 3,4-bis(octan-3-yloxy)thiophene,differing only in the alkylated thiophene-bridges.Both acceptors exhibit low optical gaps(∼1.43 eV)and possess deep highest occupied molecular orbital(HOMO)levels(∼−5.8 eV).Notably,the single-crystal structure of 3TEH demonstrates highly planar conjugated backbone and strongπ-πstacking between intermolecular terminal groups,attributed to the presence of the bulky alkylated noncovalently conformational locks.Upon utilizing both acceptors to fabricate OSCs,the 3TC8-based device exhibited a power conversion efficiency(PCE)of 11.1%,while the 3TEH-based OSC demonstrated an excellent PCE of 14.4%.This PCE is the highest among OSCs based on terthiophene-containing electron acceptors.These results offer a new strategy for designing low-cost electron acceptors for highly efficient OSCs.

Lasing dynamics study by femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy

Femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy （FNOPAS） is a versatile technique with advantages of high sensitivity, broad detection bandwidth, and intrinsic spectrum correction func- tion. These advantages should benefit the study of coherent emission, such as measurement oflasing dynamics. In this letter, the FNOPAS was used to trace the lasing process in Rhodamine 6G （R6G） solution and organic semiconductor nano-wires. High-quality transient emission spectra and lasing dynamic traces were acquired, which demonstrates the applicability of FNOPAS in the study of lasing dynamics. Our work extends the application scope of the FNOPAS technique.

Rational design of graphyne-based dual-atom site catalysts for CO oxidation

There are increasing concerns about the environmental impact of rising atmospheric carbon monoxide concentrations,thus it is necessary to develop new catalysts for efficient CO oxidation.Based on first-principles calculations,the potential ofγ-graphyne(GY)as substrate for metals in the 4th and 5th periods under single-atom and dual-atoms concentration modes has been systematically investigated.It was found that single-atom Co,Ir,Rh,and Ru could effectively oxidate CO molecules,especially for single Rh.Furthermore,proper atoms concentration could boost the CO oxidation activity by supplying more reaction centers,such as Rh^(2)/GY.It was determined that two Rh atoms in Rh^(2)/GY act different roles in the catalytic reaction:one structural and another functional.Screening tests suggest that substituting the structural Rh atom in the center of acetylenic ring by Co or Cu atom is a possible way to maintain the reaction performance while reducing the noble metal cost.This systemic investigation will help in understanding the fundamental reaction mechanisms on GY-based substrates.We emphasize that properly exposed frontier orbital of functional metal atom is crucial in adsorption configuration as well as entire catalytic performance.This study constructs a workflow and provides valuable information for rational design of CO oxidation catalysts.

Ultra-long room temperature phosphorescence of indium-based organic inorganic metal halides for naked-eye-visible afterglow

Solid-state molecules based on room-temperature phosphorescent(RTP)emission have received extensive attention due to their special optical properties of triplet excitons.However,there are still few solid molecular systems with naked-eye-visible afterglow characteristics.Herein,we introduce 4-phenylbenzylamine(namely PBA)with a long conjugated system into common non-toxic In^(3+)to form an indium-based organic inorganic halide,whose chemical formula is PBA_(3)[InCl_6]·H_(2)O.Interestingly,this hybrid halide generates a RTP emission at 617 nm with a lifetime decay as long as 290.4 ms,expressing a naked-eye-visible afterglow for more than 7 s.The mechanism study shows that the long lifetime RTP originated from the specific lamellar stacking of organic molecules and metal halide units,facilitating the interaction between the inorganic layers and organic layers.Therefore,the material can be potentially used in emergency lighting,information security,and other fields.Meanwhile,this work provides a reference for the design and implementation of a more efficient organic-inorganic hybrid system with the ultralong RTP emission.

Gradient-crosslinked hydrogel microdome pattern for multilevel chromatic encryption

In the realm of modern cryptography and anti-counterfeiting,innovative approaches are crucial to encode sensitive information securely.Tailored responsive structural colors have garnered significant interest due to their feature-rich spectra and high sensitivity to external stimuli.However,high costs and complex processing involved in integrating the various delicate microstructures have impeded their widespread development.In this study,we present a straightforward multilevel chromatic encryption scheme utilizing direct-writing gradient-crosslinked microdomes.The solvent-responsive structural color of each microdome,arising from the synergistic effect of total internal reflections and interference,is adjusted independently across the entire visible region.Each microdome functions as a signal recording unit,enabling multilevel color variations through a solventdependent development step.This approach facilitates the encoding of enhanced information into a single pixel.To demonstrate the efficacy of our method for advanced applications,we have prepared a collection of solvent-dependent multilevel codes for algorithm cryptography,showcasing its potential for high-level anti-counterfeiting and high-density optical data storage.

High performance organic transistors and phototransistors based on diketopyrrolopyrrole-quaterthiophene copolymer thin films fabricated via low-concentration solution processing

Conjugated polymers have received considerable attentions over the past years due to their large-area potential applications via low-cost solution processing. Improving crystallinity of conjugated polymer molecules in solution-processed thin films is crucial for their efficient charge transport and thus high performance optoelectronic devices. Herein, with diketopyrrolopyrrole-quaterthiophene （PDQT） copo/ymer as an example, it is found that by simply reducing the solution concentration for spincoating meanwhile with the assistance of post-annealing, significantly enhanced film crystallinity with formation of typical single crystalline domains is obtained, which benefits from the enough space for better molecular assembly especially at the semiconductor/dielectric interface. High performance polymer transistors and phototransistors were finally constructed based on the optimal lowconcentration （2 mg/mL） spin-coated PDQT films （～12 nm）, which giving a high charge carrier mobility of 2.28 cm2 V-1 s-1 and a photoresponse on/off ratio of 2.1 ×107 at VG = 0 V under white light irradiation of 6mW/cm2. The results suggest that the bright future of PDQT crystalline films for large-area flexible integrated optoelectronic devices and the application of effective low-concentration processing approach in solution-processed organic electronics with reduced material waste.

Cobalt diselenide (001) surface with short-range Co-Co interaction triggering high-performance electrocatalytic oxygen evolution

Oxygen evolution reaction (OER) still suffers from the bottleneck in electrocatalytic water splitting. Herein, in virtue of volcano plots drawn by theoretical calculation, the (001) facet was screened as the superb facet of orthorhombic CoSe_(2) for OER. Afterwards, CoSe_(2)(001) nanosheets were synthesized and the exposure ratio of (001) facet is controllable with thermodynamics methods effectively. The single-facet CoSe2(001) delivered an overpotential as low as 240 mV at 10 mA·cm^(−2) in 1 M KOH, which outperformed the bulk (380 mV) as well as other CoSe_(2)-base OER catalysts reported before. Especially, a shorter Co-Co path was observed in CoSe_(2)(001) by X-ray absorption spectroscopy. Further density functional theory (DFT) studies revealed that the reversible compression on the shorter Co-Co path could regulate the electronic structure of active sites during the OER process, and thus the energy barrier of the rate-determining step was reduced by 0.15 eV. This work could inspire more insights on the modification of electronic structure for OER electrocatalysts.

Tuning crystal polymorphs of a π-extended tetrathiafulvalene-based cruciform molecule towards high-performance organic field-effect transistors

It is a common phenomenon for organic semi- conductors to crystallize in two or more polymorphs, leading to various molecular packings and different charge transport properties. Therefore, it is a crucial issue of tuning molec- ular crystal polymorphs （i.e., adjusting the same molecule with different packing arrangements in solid state） towards efficient charge transport and high performance devices. Here, the choice of solvent had a marked effect on con- trolling the growth of a-phase ribbon and β-phase platelet during crystallization for an indenofluorene （IF） π-extended tetrathiafulvalene （TTF）-based cruciform molecule, named as IF-TTF. The charge carrier mobility of the a-phase IF-TTF crystals was more than one order of magnitude higher than that of β-phase crystals, suggesting the importance of reasonably tuning molecular packing in solid state for the improvement of charge transport in organic semiconductors.

Polarity-activated super-resolution imaging probe for the formation and morphology of amyloid fibrils

The formation of amyloid plaques usually occurs in the early-stage of Alzheimer’s disease(AD).Stimulated emission depletion(STED)imaging provided a powerful tool for visualizing amyloid structures on the nanometer scale.However,many commercial probes adopted in detecting amyloid fibrils are inapplicable to STED imaging,owing to their unmatched absorption and emission wavelengths,small Stokes'shift,easy photo-bleaching,etc.Herein,we demonstrated a polarity-activated STED probe based on an intramolecular charge transfer donor(D)-7c-acceptor(A)compound.The electron-rich carbazole group and the electron-poor pyridinium bromide group,linked by 7i-conjugated thiophen-bridge,ensure strong near infrared(NIR)emission with a Stokes'shift larger than 200 nm.The tiny change in polarity before and after binding with amyloid plaques leads to a transition from weakly emission charge-transfer(CT)state(Φ<0.04)to highly emissive locally-excited(LE)state(Φ=0.57),giving rise to a fluorescence Turn-On probe.Together with large Stokes'shift,good photostability and high depletion efficiency,the super-resolution imaging of the formation and morphology of amyloid fibrils in vitro based on this probe was realized with a lateral spatial resolution better than 33 nm at an extremely low depletion power.Moreover,the ex-vivo super-resolution imaging of(E)-1-butyl-4(2-(5-(9-ethyl-9Hcarbazol-3-yl)thiophen-2-yl)vinyl)pyridinium bromide(CTPB)probe in Aβ plaques in the brain slices of a Tg mouse was demonstrated.This research provides a demonstration of the super resolution imaging probe of amyloid fibrils based on polarity-response mechanism,providing a new approach to the development of future amyloid probes.

Multichannel Lanthanide-Doped Nanoprobes Improve Diagnostic Performance

CONSPECTUS:Diagnostics are vital in healthcare services because of their ability to reveal disease occurrence and evaluate therapeutic performance.Recent advances in nanoprobes have revolutionized the diagnostics field.These nanoprobes typically contain one or more signal channels;thereby,they are able to quantify chemical signals or locate spatial indicators upon signal collection.It is noteworthy that multichannel nanoprobes have more merits than conventional single-channel ones,which has recently attracted significant interest.A benefit of this approach is that multiple signals will generate more information in one single test,which avoids omitting details and reduces the risk of false results.Additionally,multiple signals give more instrumentation options to operators,which allows diagnostics in broad clinical conditions.As a result,multichannel nanoprobes are ideal tools to increase diagnostic performance.Due to the specific 4f electrons,lanthanide ions have simultaneous and extraordinary electric,optical,and magnetic capacities.Therefore,lanthanide-doped nanomaterials are advanced candidates for fabricating multichannel nanoprobes and hence are favorable for biological and medical studies.In this Account,we highlight recent progress in designing multichannel lanthanide-doped nanoprobes to improve biomolecule detection and diagnostic performance with a particular focus on our own work.First,we present a brief overview on the type of signals that are available for constructing multichannel nanoprobes.The principles and merits of each signal are highlighted.Then,we summarize the general strategies of integrating multiple types of signals into one nanoprobe.Using this strategy,we have fabricated a series of multichannel lanthanide-doped nanoprobes and have explored their potential to improve diagnostic precision from different aspects.Finally,we propose an outlook on future development and possible issues of next-generation lanthanidedoped nanoprobes with multiple signal channels.We hope this timely account can update our understanding of multifunctional nanoprobes in medicine and provide some helpful references for the state-of-art diagnostic protocols with outstanding performance.

Efficient Small-Molecule Organic Solar Cells by Modulating Fluorine Substitution Position of Donor Material

Comprehensive Summary The fluorine substitution position in organic semiconductors is critical in improving device performance for organic solar cells(OSCs).Herein,two similar small-molecule donors,B3T-PoF and B3T-PmF,are designed and synthesized,which only differ on the fluorine substitution position on the pendent benzene unit.Although both small-molecule donors exhibit similar absorption profiles and molecular energy levels,B3T-PmF has stronger crystallinity and lower energetic disorder than B3T-PoF.After blending with the non-fullerene acceptor of BO-4Cl,B3T-PmF shows better phase separation and more ordered molecular packing in blend film.As a result,the B3T-PoF:BO-4Cl-based OSC shows a power conversion efficiency(PCE)of 12.3%.In contrast,the B3T-PmF:BO-4Cl-based cell demonstrates obviously increased JSC and FF values,thus yielding an excellent PCE of 14.7%.This study indicates that reasonable selection of fluorine atom substitution position in conjugated side chains is one of the promising strategies for achieving high-performance SM-DSCs.

Aromaticity Concerto in Polycyclic Conjugated Hydrocarbons:Fusion Pattern on Combined Aromaticity Strategy Leads to Distinctive Excited State Photophysics of Dinaphthopentalenes

Understanding the structure-property relationships in polycyclic conjugated hydrocarbons(PCHs)is crucial in controlling their electronic properties and developing new optically functional materials.Aromaticity is a fundamentally important and intriguing property of numerous organic chemical structures and has stimulated a myriad of experimental and theoretical investigations.Exploiting aromaticity rules for the rational design of optoelectronic materials with the desired photophysical characteristics is a challenging yet fascinating task.Herein we present an in-depth computational and spectroscopic study on the structure-property relationships of dinaphthopentalenes(DNPs).Results highlight that the different fusion patterns between 4nπand 4n+2πunits endow these PCHs with the tunable aromaticity in the ground state/excited state,which leads to the diverse electronic structures and consequently the distinctive excited state photophysics.Accordingly,we propose a combined aromaticity design strategy for rationally modulating and tailoring electronic and optical properties of PCH skeletons.These outcomes not only present a full picture of the excited state dynamics of the DNP system and afford a new class of efficient singlet fission-active materials but also provide some basic guidelines for exploiting aromaticity rules to design and develop new optical function materials.

Organic single-crystal phototransistor with unique wavelength-detection characteristics

Organic phototransistors based on high-quality 2,8-dichloro-5,11-dihexyl-indolo[3,2-b]carbazo(CHICZ)single crystals show the highest photoresponsivity of 3×10^3 A W^-1, photosensitivity of 2×10^4 and the detectivity can achieve 8.4×10^14 Jones. We also discovered good linear dependence of log(photosensitivity) versus the wavelength when the devices were illuminated with a series of sameintensity but different-wavelength lights. The organic phototransistors based on CHICZ single crystal have potential applications in wavelength-detection.

A new fluorescent quinoline derivative toward the acid-responsivity in both solution and solid states

In this article,an acid-responsive luminescent material,1,4-di(quinoline-6-yl)buta-1,3-diyne(DQBD)is designed and synthesized.Upon different pH values,gradual changes of fluorescence colors for DQBD in both solution and solid phases are demonstrated due to the protonation effect.Moreover,such responsive characteristics can also be reversible,suggesting DQBD as a promising fluorescent material with great potential for reusable-and accurate-p H sensors in the future.

Tunable amplified spontaneous emissions by dimensional-controlled microcrystal synthesis

The excited-state intramolecular proton transfer molecules based on chalcone （E）-3-（4＇-dimethylami- nophenyl）-l-（4＇-fluoro-2＇-hydroxyphenyl）-2-propen-l-one （DMF-HPPO） have been synthesized under microwave irradiation. One-dimensional （1D） microwires and 2D microdisks of DMF-HPPO have been selectively prepared by controlling the solution polarity. XRD results revealed the two microcrystals exhibit distinct diffraction patterns, which indicates that they have belonged to different crystalline nature. The microcrystals demonstrate shape-dependent amplified spontaneous emissions （ASE） that the emission of ID microwire is central around 618 nm and the 2D microdisk emits fluorescence at 650 nm. This result reveals the controlled synthesis of two microcrystals and their consequent multicolor amplified spontaneous emission, providing considerable promise for the development and application of new opto-electronic devices.

Organic polaritonic light-emitting diodes with high luminance and color purity toward laser displays

Achieving high-luminescence organic light-emitting devices(OLEDs)with narrowband emission and high color purity is important in various optoelectronic fields.Laser displays exhibit outstanding advantages in next-generation display technologies owing to their ultimate visual experience,but this remains a great challenge.Here,we develop a novel OLED based organic single crystals.By strongly coupling the organic exciton state to an optical microcavity,we obtain polariton electroluminescent(EL)emission from the polariton OLEDs(OPLEDs)with high luminance,narrow-band emission,high color purity,high polarization as well as excellent optically pumped polariton laser.Further,we evaluate the potential for electrically pumped polariton laser through theoretical analysis and provide possible solutions.This work provides a powerful strategy with a material–device combination that paves the way for electrically driven organic single-crystal-based polariton luminescent devices and possibly lasers.

Acceptor-Type Singlet Fission Material Based on Strong Absorption Tetracyanothienoquinoid Skeleton

The practical efficiency of singlet fission(SF)-based photovoltaic devices is still far from satisfactory due to the limited scope of SF materials suitable for device application and the scarcity of schemes available for triplet utilization.Most SF materials identi-fied to date are typically electron donors while acceptor-type SF materials remain largely unexplored.Basically,the combination of a conventional electron donor and SF-active electron acceptor could circumvent the competitive energy transfer channel and better play the unique advantages of the SF process,which might be an adequate alternative for practical application.In this work,we presented a new acceptor-type SF material based on a tetracyanothienoquinoid skeleton.Such a quinoid skeleton exhibited strong absorption,ultrafast SF process,and excellent stability.Using transient spectroscopy and multireference calculations(XDWCASPT2),the SF dynamics were examined featuring the rapid generation and subsequent annihilation and/or partial dissociation of multiexciton states.Therefore,our results not only provide a robust acceptor-type SF material but also suggest an adequate donor–acceptor alternative for SF-based solar cells,which could pave the way for the practical application of such a potential process.

What Can Topology Bring to Chemistry?

The unique mathematical perspectives and principal concepts of topology have not only promoted the development of other branches of mathematics but have also deeply influenced other subjects,particularly physics and chemistry.This minireview aims to elucidate the substantial influence of topology on chemistry by critically examining both the contributions of topology to current chemical science and its potential future impacts.We will discuss the topology of molecular structures and assemblies across various scales—from small molecules and mechanically interlocked molecules to polymers,biomacromolecules,and supramolecular networks.This discussion will include an exploration of cutting-edge techniques for characterizing topological features,underscoring the role of topology as a novel paradigm for the design and synthesis of new molecular assemblies.Furthermore,a critical analysis of topology’s role in the development of functional materials—such as photonic materials,polymers,biomacromolecules,and chiral materials—will demonstrate its emerging significance as a crucial parameter in unveiling novel properties and functionalities.Given topology’s formidable potential,it is anticipated to be used increasingly to address pivotal challenges within chemistry and adjacent disciplines.