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 d...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.展开更多
In this study,biochar(BC)derived from pomelo was prepared via a high-temperature calcination method to modify the graphitic carbon nitride(g-C_(3)N_(4))to synthesize the BC/g-C_(3)N_(4)composite for the degradation of...In this study,biochar(BC)derived from pomelo was prepared via a high-temperature calcination method to modify the graphitic carbon nitride(g-C_(3)N_(4))to synthesize the BC/g-C_(3)N_(4)composite for the degradation of the tetracycline(TC)antibiotic under visible light irradiation.The experimental results exhibit that the optimal feeding weight ratio of biochar/urea is 0.03:1 in BC/g-C_(3)N_(4)composite could show the best photocatalytic activity with the degradation rate of tetracycline is 83%in 100 min irradiation.The improvement of photocatalytic activity is mainly attributed to the following two points:(i)the strong bonding with π-π stacking between BC and g-C_(3)N_(4)make the photogenerated electrons of light-excited g-C_(3)N_(4)transfer to BC,quickly and improve the separation efficiency of carriers;(ii)the introduction of BC reduces the distance for photogenerated electrons to migrate to the surface and increases the specific surface area for providing more active sites.This study provides a sustainable,economical and promising method for the synthesis of photocatalytic materials their application to wastewater treatment.展开更多
The effect of the electron acceptors H2O2 and O2 on the type of generated reactive oxygen species(ROS),and glycerol conversion and product distribution in the TiO2-catalyzed photocatalytic oxidation of glycerol was ...The effect of the electron acceptors H2O2 and O2 on the type of generated reactive oxygen species(ROS),and glycerol conversion and product distribution in the TiO2-catalyzed photocatalytic oxidation of glycerol was studied at ambient conditions.In the absence of an electron acceptor,only HO^·radicals were generated by irradiated UV light and TiO2.However,in the presence of the two electron acceptors,both HO^· radical and ^1O2 were produced by irradiated UV light and TiO2 in different concentrations that depended on the concentration of the electron acceptor.The use of H2O2 as an electron acceptor enhanced glycerol conversion more than O2.The type of generated value-added compounds depended on the concentration of the generated ROS.展开更多
Fullerenes and their derivatives are important types of electron acceptor materials and play a vital role in organic solar cell devices. However, the fullerene acceptor material has some difficulties to overcome the i...Fullerenes and their derivatives are important types of electron acceptor materials and play a vital role in organic solar cell devices. However, the fullerene acceptor material has some difficulties to overcome the intrinsic shortcomings, such as weak absorption in the visible range, difficulty in modification and high cost, which limit the performance of the device and the large-scale application of this type of acceptors. In recent years, non-fullerene electron acceptor material has attracted the attention of scientists due to the advantages of adjustable energy level, wide absorption, simple synthesis, low processing cost and good solubility. Researchers can use the rich chemical means to design and synthesize organic small molecules and their oligomers with specific aggregation morphology and excellent optoelectronic prop- erties. Great advances in the field of synthesis, device engineering, and device physics of non-fullerene acceptors have been achieved in the last few years. At present, non-fullerene small molecules based photovoltaic devices achieve the highest efficiency more than 13% and the efficiency gap between fullerenetype and non-fullerene-type photovoltaic devices is gradually narrowing. In this review, we explore recent progress of non-fullerene small molecule electron acceptors that have been developed and led to highefficiency photovoltaic devices and put forward the prospect of development in the future.展开更多
Non-fullerene polymer solar cells(NF-PSCs) have gained wide attention recently. Molecular design of non-fullerene electron acceptors effectively promotes the photovoltaic performance of NF-PSCs. However,molecular elec...Non-fullerene polymer solar cells(NF-PSCs) have gained wide attention recently. Molecular design of non-fullerene electron acceptors effectively promotes the photovoltaic performance of NF-PSCs. However,molecular electron acceptors with 2-dimensional(2 D) configuration and conjugation are seldom reported.Herein, we designed and synthesized a series of novel 2 D electron acceptors for efficient NF-PSCs. With rational optimization on the conjugated moieties in both vertical and horizontal direction, these 2 D electron acceptors showed appealing properties, such as good planarity, full-spectrum absorption, high absorption extinction coefficient, and proper blend morphology with donor polymer. A high PCE of 9.76%was achieved for photovoltaic devices with PBDB-T as the donor and these 2 D electron acceptors. It was also found the charge transfer between the conjugated moieties in two directions of these 2 D molecules contributes to the utilization of absorbed photos, resulting in an exceptional EQE of 87% at 730 nm. This work presents rational design guidelines of 2 D electron acceptors, which showed great promise to achieve high-performance non-fullerene polymer solar cells.展开更多
Characteristics of phosphorus removal bacteria were investigated by using three different types of electron acceptors, as well as the positive role of nitrite in phosphorus removal process. An (AO)^2 SBR (anaerobic...Characteristics of phosphorus removal bacteria were investigated by using three different types of electron acceptors, as well as the positive role of nitrite in phosphorus removal process. An (AO)^2 SBR (anaerobic-aerobic-anoxic-aerobic sequencing batch reactor) was thereby employed to enrich denitrifying phosphorus removal bacteria for simultaneously removing phosphorus and nitrogen via auoxic phosphorus uptake, Ammonium oxidation was controlled at the first phase of the nitrification process. Nitrite-inhibition batch tests illustrated that nitrite was not an inhibitor to phosphorus uptake process, but served as an alternative electron acceptor to nitrate and oxygen if the concentration was under the inhibition level of 40mg NO2 - N·L^- 1. It implied that in addition to the two well-accepted groups of phosphorus removal bacterium ( one can only utilize oxygen as electron acceptor, P1, while the other can use both oxygen and nitrate as electron acceptor, P2 ), a new group of phosphorus removal bacterium P3, which could use oxygen, nitrate and nitrite as electron acceptor to take up phosphorus were identified in the test system. To understand (AO)^2 SBR sludge better, the relative population of the different bacteria in this system, plus another A/O SBR sludge ( seed sludge) were respectively estimated by the phosphorus uptake batch tests with either oxygen or nitrate or nitrite as electron acceptor. The results demonstrated that phosphorus removal capability of (AO)^2 SBR sludge had a little degradation after A/O sludge was cultivated in the (AO)^2 mode over a long period of time. However, deuitrifying phosphorus removal bacteria ( P2 and P3 ) was significantly enriched showed by the relative population of the three types of bacteria, which implied that energy for aeration and COD consumption could be reduced in theory.展开更多
Photoinduced charge transfer polymerization of styrene(St) with electron acceptor as initiator was investigated. In case of fumaronitrile (FN) or maleic anhydride (MA) as initiator the polymerization takes place regul...Photoinduced charge transfer polymerization of styrene(St) with electron acceptor as initiator was investigated. In case of fumaronitrile (FN) or maleic anhydride (MA) as initiator the polymerization takes place regularly, whereas the tetrachloro-1,4-benzenequinone (TCQ), 2,3-dichloro-5, 6-dicyano-1, 4-benzenequinone (DDQ). or tetracyano ethylene (TCNE) as initiator the polymerization proceeds reluctantly only after the photoaddition reaction. A mechanism was proposed that free radicals would be formed following the charge and proton transfer in the exciplex formed between St and electron accepters.展开更多
Small molecule ladder-type heteroarenes IHBT-2F is designed and synthesized with strong electrondonating and molecular packing properties, where the central unit, fused thienobenzene-thienothiphene (IHBT), is attached...Small molecule ladder-type heteroarenes IHBT-2F is designed and synthesized with strong electrondonating and molecular packing properties, where the central unit, fused thienobenzene-thienothiphene (IHBT), is attached with the strong electron-deficient 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (2FIC) as the end group. The counterpart IDBT-2F with indancenodibenzothiophene (IDBT) mainchain is sythesized for comparison, in which thieno[3,2-b]thiophene (TT) core of IHBT is replaced by benzene core. Relative to benzene-core IDBT-2F, TT-core IHBT-2F shows a much higher highest occupied molecular orbital energy level (IHBT-2F:-5.46 eV;IDBT-2F:-5.72 eV) and significantly redshifted absorption, due to the π-donor capability of the sulfur atom, the larger π-conjugation and stronger intermolecular π-π stacking. The as-cast organic solar cells (OSCs) based on blends of PTB7-Th donor and IHBT-2F acceptor without additional treatments exhibit power conversion efficiencies (PCEs) as high as 8.74%, which is much higher than that of PTB7-Th:IDBT-2F (6.73%).展开更多
Reduced rate constants of photoinduced electron transfer in intramolecular fluorescence quenching of donor-acceptor podands induced by cation-complexation are observed in the highly exothermic reactions.
Using depletion approximation theory and introducing acceptor defects which can characterize radiation induced deep-level defects in AlGaN/GaN heterostructures,we set up a radiation damage model of AlGaN/GaN high elec...Using depletion approximation theory and introducing acceptor defects which can characterize radiation induced deep-level defects in AlGaN/GaN heterostructures,we set up a radiation damage model of AlGaN/GaN high electron mobility transistor (HEMT) to separately simulate the effects of several main radiation damage mechanisms and the complete radiation damage effect simultaneously considering the degradation in mobility. Our calculated results,consistent with the experimental results,indicate that thin AlGaN barrier layer,high Al content and high doping concentration are favourable for restraining the shifts of threshold voltage in the AlGaN/GaN HEMT;when the acceptor concentration induced is less than 10^14cm-3,the shifts in threshold voltage are not obvious;only when the acceptor concentration induced is higher than 10^16cm-3,will the shifts of threshold voltage remarkably increase;the increase of threshold voltage,resulting from radiation induced acceptor,mainly contributes to the degradation in drain saturation current of the current-voltage (Ⅰ-Ⅴ) characteristic,but has no effect on the transconductance in the saturation area.展开更多
Developing narrow-bandgap organic semiconductors is important to facilitate the advancement of organic photovoltaics(OPVs). Herein, two near-infrared non-fused ring acceptors(NIR NFRAs), PTBFTT-F and PTBFTT-Cl have be...Developing narrow-bandgap organic semiconductors is important to facilitate the advancement of organic photovoltaics(OPVs). Herein, two near-infrared non-fused ring acceptors(NIR NFRAs), PTBFTT-F and PTBFTT-Cl have been developed with A-π_A-π_D-D-π_D-π_A-A non-fused structures. It is revealed that the introduction of electron deficient π-bridge(π_A) and multiple intramolecular noncovalent interactions effectively retained the structural planarity and intramolecular charge transfer of NFRAs, extending strong NIR photon absorption up to 950 nm. Further, the chlorinated acceptor, with the enlarged π-surface compared to the fluorinated counterpart, promoted not only molecular stacking in solid, but also the desirable photochemical stability in ambient, which are helpful to thereby improve the exciton and charge dynamics for the corresponding OPVs. Overall, this work provides valuable insights into the design of NIR organic semiconductors.展开更多
By employing the asymmetric end-group engineering,an asymmetric nonfused-ring electron acceptor(NFREA)was designed and synthesized.Compared with the symmetric analogs(NoCA-17 and NoCA-18),NoCA-19 possesses broader lig...By employing the asymmetric end-group engineering,an asymmetric nonfused-ring electron acceptor(NFREA)was designed and synthesized.Compared with the symmetric analogs(NoCA-17 and NoCA-18),NoCA-19 possesses broader light absorption range,more coplanarπ-conjugated backbone,and appropriate crystallinity according to the experimental and theoretical results.The organic solar cells based on J52:NoCA-19 exhibited a power conversion efficiency as high as 12.26%,which is much higher than those of J52:NoCA-17(9.50%)and J52:NoCA-18(11.77%),mainly due to more efficient exciton dissociation,better and balanced charge mobility,suppressed recombination loss,shorter charge extraction time,longer charge carrier lifetimes,and more favorable blend film morphology.These findings demonstrate the great potential of asymmetric end-group engineering in exploring low-cost and high-performance NFREAs.展开更多
At room temperature,the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane(DRM) is quite promising and challenging.Herein,we developed a novel covalent organ...At room temperature,the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane(DRM) is quite promising and challenging.Herein,we developed a novel covalent organic porous polymer (TPE-COP) with rapid charge separation of the electron–hole pairs for DRM driven by visible light at room temperature,which can efficiently generate syngas (CO and H_(2)).Both electron donor (tris(4-aminophenyl)amine,TAPA) and acceptor (4,4',4'',4'''-((1 E,1'E,1''E,1'''E)-(ethene-1,1,2,2-tetrayltetrakis (benzene-4,1-diyl))tetrakis (ethene-2,1-diyl))tetrakis (1-(4-formylbenzyl)quinolin-1-ium),TPE-CHO) were existed in TPE-COP,in which the push–pull effect between them promoted the separation of photogenerated electron–hole,thus greatly improving the photocatalytic activity.Density functional theory (DFT) simulation results show that TPE-COP can form charge-separating species under light irradiation,leading to electrons accumulation in TPE-CHO unit and holes in TAPA,and thus efficiently initiating DRM.After 20 h illumination,the photocatalytic results show that the yields reach 1123.6 and 30.8μmol g^(-1)for CO and H_(2),respectively,which are significantly higher than those of TPE-CHO small molecules.This excellent result is mainly due to the increase of specific surface area,the enhancement of light absorption capacity,and the improvement of photoelectron-generating efficiency after the formation of COP.Overall,this work contributes to understanding the advantages of COP materials for photocatalysis and fundamentally pushes metal-free catalysts into the door of DRM field.展开更多
基金supported by the Beijing Natural Science Foundation of China(Z230019,2212005)the National Natural Science Foundation of China(NSFC 22173062,21833005,22090022 and 22275125).
文摘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.
基金the founding support from the National Natural Science Foundation of China (21906072, 22006057 and 31971616)the Natural Science Foundation of Jiangsu Province (BK20190982)+4 种基金“Doctor of Mass Entrepreneurship and Innovation” Project in Jiangsu ProvinceHenan Postdoctoral Foundation (202003013)the Science and Technology Research Project of the Department of Education of Jilin Province (JJKH20200039KJ)the Science and Technology Research Project of Jilin City (20190104120, 201830811)the Project of Jilin Provincial Science and Technology Development Plan (20190201277JC, 20200301046RQ, YDZJ202101ZYTS070)
文摘In this study,biochar(BC)derived from pomelo was prepared via a high-temperature calcination method to modify the graphitic carbon nitride(g-C_(3)N_(4))to synthesize the BC/g-C_(3)N_(4)composite for the degradation of the tetracycline(TC)antibiotic under visible light irradiation.The experimental results exhibit that the optimal feeding weight ratio of biochar/urea is 0.03:1 in BC/g-C_(3)N_(4)composite could show the best photocatalytic activity with the degradation rate of tetracycline is 83%in 100 min irradiation.The improvement of photocatalytic activity is mainly attributed to the following two points:(i)the strong bonding with π-π stacking between BC and g-C_(3)N_(4)make the photogenerated electrons of light-excited g-C_(3)N_(4)transfer to BC,quickly and improve the separation efficiency of carriers;(ii)the introduction of BC reduces the distance for photogenerated electrons to migrate to the surface and increases the specific surface area for providing more active sites.This study provides a sustainable,economical and promising method for the synthesis of photocatalytic materials their application to wastewater treatment.
基金Chulalongkorn University Dutsadi Phiphat Scholarshipthe Ratchadapisek Sompoch Endowment Fund(Sci-Super Ⅱ GF_58_08_23_01)the Thailand Research Fund(IRG5780001) for financial support
文摘The effect of the electron acceptors H2O2 and O2 on the type of generated reactive oxygen species(ROS),and glycerol conversion and product distribution in the TiO2-catalyzed photocatalytic oxidation of glycerol was studied at ambient conditions.In the absence of an electron acceptor,only HO^·radicals were generated by irradiated UV light and TiO2.However,in the presence of the two electron acceptors,both HO^· radical and ^1O2 were produced by irradiated UV light and TiO2 in different concentrations that depended on the concentration of the electron acceptor.The use of H2O2 as an electron acceptor enhanced glycerol conversion more than O2.The type of generated value-added compounds depended on the concentration of the generated ROS.
基金the financial support by the National Natural Science Foundation of China(51303099)the Natural Science Basic Research Plan in Shaanxi Province of China(2017JM5058)the Funded Projects for the Academic Leaders and Academic Backbones,Shaanxi Normal University(16QNGG008)
文摘Fullerenes and their derivatives are important types of electron acceptor materials and play a vital role in organic solar cell devices. However, the fullerene acceptor material has some difficulties to overcome the intrinsic shortcomings, such as weak absorption in the visible range, difficulty in modification and high cost, which limit the performance of the device and the large-scale application of this type of acceptors. In recent years, non-fullerene electron acceptor material has attracted the attention of scientists due to the advantages of adjustable energy level, wide absorption, simple synthesis, low processing cost and good solubility. Researchers can use the rich chemical means to design and synthesize organic small molecules and their oligomers with specific aggregation morphology and excellent optoelectronic prop- erties. Great advances in the field of synthesis, device engineering, and device physics of non-fullerene acceptors have been achieved in the last few years. At present, non-fullerene small molecules based photovoltaic devices achieve the highest efficiency more than 13% and the efficiency gap between fullerenetype and non-fullerene-type photovoltaic devices is gradually narrowing. In this review, we explore recent progress of non-fullerene small molecule electron acceptors that have been developed and led to highefficiency photovoltaic devices and put forward the prospect of development in the future.
基金financially supported by the National Key Research and Development Program of China (No. 2019YFA0705900) funded by MOSTthe Basic and Applied Basic Research Major Program of Guangdong Province (No. 2019B030302007)the National Natural Science Foundation of China (No. 51521002)。
文摘Non-fullerene polymer solar cells(NF-PSCs) have gained wide attention recently. Molecular design of non-fullerene electron acceptors effectively promotes the photovoltaic performance of NF-PSCs. However,molecular electron acceptors with 2-dimensional(2 D) configuration and conjugation are seldom reported.Herein, we designed and synthesized a series of novel 2 D electron acceptors for efficient NF-PSCs. With rational optimization on the conjugated moieties in both vertical and horizontal direction, these 2 D electron acceptors showed appealing properties, such as good planarity, full-spectrum absorption, high absorption extinction coefficient, and proper blend morphology with donor polymer. A high PCE of 9.76%was achieved for photovoltaic devices with PBDB-T as the donor and these 2 D electron acceptors. It was also found the charge transfer between the conjugated moieties in two directions of these 2 D molecules contributes to the utilization of absorbed photos, resulting in an exceptional EQE of 87% at 730 nm. This work presents rational design guidelines of 2 D electron acceptors, which showed great promise to achieve high-performance non-fullerene polymer solar cells.
文摘Characteristics of phosphorus removal bacteria were investigated by using three different types of electron acceptors, as well as the positive role of nitrite in phosphorus removal process. An (AO)^2 SBR (anaerobic-aerobic-anoxic-aerobic sequencing batch reactor) was thereby employed to enrich denitrifying phosphorus removal bacteria for simultaneously removing phosphorus and nitrogen via auoxic phosphorus uptake, Ammonium oxidation was controlled at the first phase of the nitrification process. Nitrite-inhibition batch tests illustrated that nitrite was not an inhibitor to phosphorus uptake process, but served as an alternative electron acceptor to nitrate and oxygen if the concentration was under the inhibition level of 40mg NO2 - N·L^- 1. It implied that in addition to the two well-accepted groups of phosphorus removal bacterium ( one can only utilize oxygen as electron acceptor, P1, while the other can use both oxygen and nitrate as electron acceptor, P2 ), a new group of phosphorus removal bacterium P3, which could use oxygen, nitrate and nitrite as electron acceptor to take up phosphorus were identified in the test system. To understand (AO)^2 SBR sludge better, the relative population of the different bacteria in this system, plus another A/O SBR sludge ( seed sludge) were respectively estimated by the phosphorus uptake batch tests with either oxygen or nitrate or nitrite as electron acceptor. The results demonstrated that phosphorus removal capability of (AO)^2 SBR sludge had a little degradation after A/O sludge was cultivated in the (AO)^2 mode over a long period of time. However, deuitrifying phosphorus removal bacteria ( P2 and P3 ) was significantly enriched showed by the relative population of the three types of bacteria, which implied that energy for aeration and COD consumption could be reduced in theory.
文摘Photoinduced charge transfer polymerization of styrene(St) with electron acceptor as initiator was investigated. In case of fumaronitrile (FN) or maleic anhydride (MA) as initiator the polymerization takes place regularly, whereas the tetrachloro-1,4-benzenequinone (TCQ), 2,3-dichloro-5, 6-dicyano-1, 4-benzenequinone (DDQ). or tetracyano ethylene (TCNE) as initiator the polymerization proceeds reluctantly only after the photoaddition reaction. A mechanism was proposed that free radicals would be formed following the charge and proton transfer in the exciplex formed between St and electron accepters.
基金NSFC (21504058)NSFC/RGC Joint Research Scheme No. N_CUHK418/17+1 种基金Research Grant Council of Hong Kong (General Research Fund No. 14314216)the beam time and technical supports provided by 19U2 beamline at SSRF, Shanghai
文摘Small molecule ladder-type heteroarenes IHBT-2F is designed and synthesized with strong electrondonating and molecular packing properties, where the central unit, fused thienobenzene-thienothiphene (IHBT), is attached with the strong electron-deficient 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (2FIC) as the end group. The counterpart IDBT-2F with indancenodibenzothiophene (IDBT) mainchain is sythesized for comparison, in which thieno[3,2-b]thiophene (TT) core of IHBT is replaced by benzene core. Relative to benzene-core IDBT-2F, TT-core IHBT-2F shows a much higher highest occupied molecular orbital energy level (IHBT-2F:-5.46 eV;IDBT-2F:-5.72 eV) and significantly redshifted absorption, due to the π-donor capability of the sulfur atom, the larger π-conjugation and stronger intermolecular π-π stacking. The as-cast organic solar cells (OSCs) based on blends of PTB7-Th donor and IHBT-2F acceptor without additional treatments exhibit power conversion efficiencies (PCEs) as high as 8.74%, which is much higher than that of PTB7-Th:IDBT-2F (6.73%).
基金We are grateful to the National NatUral Science Foundation of China for support this work.!(grantNO. 29733100)
文摘Reduced rate constants of photoinduced electron transfer in intramolecular fluorescence quenching of donor-acceptor podands induced by cation-complexation are observed in the highly exothermic reactions.
基金Project supported by the National Defense Scientific and Technical Pre-Research Program of China (Grant Nos 51311050112,51308040301 and 51308030102)the National Defense Fundamental Research Program of China (Grant No A1420060156)the National Basic Research Program of China (Grant No 513270407)
文摘Using depletion approximation theory and introducing acceptor defects which can characterize radiation induced deep-level defects in AlGaN/GaN heterostructures,we set up a radiation damage model of AlGaN/GaN high electron mobility transistor (HEMT) to separately simulate the effects of several main radiation damage mechanisms and the complete radiation damage effect simultaneously considering the degradation in mobility. Our calculated results,consistent with the experimental results,indicate that thin AlGaN barrier layer,high Al content and high doping concentration are favourable for restraining the shifts of threshold voltage in the AlGaN/GaN HEMT;when the acceptor concentration induced is less than 10^14cm-3,the shifts in threshold voltage are not obvious;only when the acceptor concentration induced is higher than 10^16cm-3,will the shifts of threshold voltage remarkably increase;the increase of threshold voltage,resulting from radiation induced acceptor,mainly contributes to the degradation in drain saturation current of the current-voltage (Ⅰ-Ⅴ) characteristic,but has no effect on the transconductance in the saturation area.
基金funded by National Natural Science Foundation of China (No.22125901)the National Key Research and Development Program of China (No.2019YFA0705900)the Fundamental Research Funds for the Central Universities (No.226–2023–00113)。
文摘Developing narrow-bandgap organic semiconductors is important to facilitate the advancement of organic photovoltaics(OPVs). Herein, two near-infrared non-fused ring acceptors(NIR NFRAs), PTBFTT-F and PTBFTT-Cl have been developed with A-π_A-π_D-D-π_D-π_A-A non-fused structures. It is revealed that the introduction of electron deficient π-bridge(π_A) and multiple intramolecular noncovalent interactions effectively retained the structural planarity and intramolecular charge transfer of NFRAs, extending strong NIR photon absorption up to 950 nm. Further, the chlorinated acceptor, with the enlarged π-surface compared to the fluorinated counterpart, promoted not only molecular stacking in solid, but also the desirable photochemical stability in ambient, which are helpful to thereby improve the exciton and charge dynamics for the corresponding OPVs. Overall, this work provides valuable insights into the design of NIR organic semiconductors.
基金the financial support fromtheNSFC(21975055,U2001222,52103352,52120105006,and 51925306)National Key R&D Program of China(2018FYA 0305800)+2 种基金Key Research Program of Chinese Academy of Sciences(XDPB08-2)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2022165)the Fundamental Research Funds for the Central Universities.DFT results described in this article were obtained from the National Supercomputing Centre in Shenzhen(Shenzhen Cloud Computing Centre).
文摘By employing the asymmetric end-group engineering,an asymmetric nonfused-ring electron acceptor(NFREA)was designed and synthesized.Compared with the symmetric analogs(NoCA-17 and NoCA-18),NoCA-19 possesses broader light absorption range,more coplanarπ-conjugated backbone,and appropriate crystallinity according to the experimental and theoretical results.The organic solar cells based on J52:NoCA-19 exhibited a power conversion efficiency as high as 12.26%,which is much higher than those of J52:NoCA-17(9.50%)and J52:NoCA-18(11.77%),mainly due to more efficient exciton dissociation,better and balanced charge mobility,suppressed recombination loss,shorter charge extraction time,longer charge carrier lifetimes,and more favorable blend film morphology.These findings demonstrate the great potential of asymmetric end-group engineering in exploring low-cost and high-performance NFREAs.
基金supported by National Natural Science Foundation of China (Nos. 22274039 and 22178089)Hunan Provincial Innovation Foundation for Postgraduate (No.CX20220392)。
文摘At room temperature,the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane(DRM) is quite promising and challenging.Herein,we developed a novel covalent organic porous polymer (TPE-COP) with rapid charge separation of the electron–hole pairs for DRM driven by visible light at room temperature,which can efficiently generate syngas (CO and H_(2)).Both electron donor (tris(4-aminophenyl)amine,TAPA) and acceptor (4,4',4'',4'''-((1 E,1'E,1''E,1'''E)-(ethene-1,1,2,2-tetrayltetrakis (benzene-4,1-diyl))tetrakis (ethene-2,1-diyl))tetrakis (1-(4-formylbenzyl)quinolin-1-ium),TPE-CHO) were existed in TPE-COP,in which the push–pull effect between them promoted the separation of photogenerated electron–hole,thus greatly improving the photocatalytic activity.Density functional theory (DFT) simulation results show that TPE-COP can form charge-separating species under light irradiation,leading to electrons accumulation in TPE-CHO unit and holes in TAPA,and thus efficiently initiating DRM.After 20 h illumination,the photocatalytic results show that the yields reach 1123.6 and 30.8μmol g^(-1)for CO and H_(2),respectively,which are significantly higher than those of TPE-CHO small molecules.This excellent result is mainly due to the increase of specific surface area,the enhancement of light absorption capacity,and the improvement of photoelectron-generating efficiency after the formation of COP.Overall,this work contributes to understanding the advantages of COP materials for photocatalysis and fundamentally pushes metal-free catalysts into the door of DRM field.