Efficient heterojunction organic photovoltaic (OPV) cells are fabricated based on copper tetra-methyl phthalocyanine (CuMePc) as donor and fullerene (C60) as acceptor. The power conversion efficiency of CuMePc/C...Efficient heterojunction organic photovoltaic (OPV) cells are fabricated based on copper tetra-methyl phthalocyanine (CuMePc) as donor and fullerene (C60) as acceptor. The power conversion efficiency of CuMePc/C60 OPV cell (2.52%) is increased by 88% compared with that of the non-peripheral substituted copper phthalocyanine (CuPc)/C60 OPV cell (1.34%). The introduction of methyl substituent leads to stronger π–π interaction of CuMePc (~ 3.5 ?) than that of CuPc (~ 3.8 ?). The efficiency improvement is attributed to the enhanced carrier mobility of CuMePc thin film (1.1×10-3 cm2/V·s) and better film morphology by introducing methyl groups into the periphery of CuPc molecule.展开更多
Organic photovoltaic cells have been fabricated using copper phthalocyanine CuPc as electron donor and C60 or PCBM as electron acceptor. We have investigated the I-V measurements of two different structures: ITO/PEDOT...Organic photovoltaic cells have been fabricated using copper phthalocyanine CuPc as electron donor and C60 or PCBM as electron acceptor. We have investigated the I-V measurements of two different structures: ITO/PEDOT: PSS/(CuPc:C60 or CuPc:PCBM)/BCP/Al. We have observed that the substitution of PCBM by C60 scales up the photocurrent and the efficiency of the devices. As for the open-circuit voltage and the fill factor, we have seen that Voc and FF depend on the energy difference between the highest occupied molecular orbital (HOMO) of CuPc and the lowest unoccupied molecular orbital (LUMO)of C60 or PCBM.展开更多
The influence of an ultrathin 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) fluorescent dye layer at donor/acceptor heterojunction on the performance of small-molecule o...The influence of an ultrathin 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) fluorescent dye layer at donor/acceptor heterojunction on the performance of small-molecule organic photovoltaic (OPV) cell is studied. The structure of OPV cell is of indium-tin oxide (ITO)/copper phthalocyanine (CuPc)/DCJTB/fullerene (C60)/bathophenantbroline (Bphen)/Ag. The results show that open circuit voltage (Voc) increases to 0.57 V as the film thickness of DCJTB layer increases from 0.2 to 2.0 nm. By using an equivalent circuit model, the enhancement of VOC is found to be attributed to the reduced reverse saturation current density (Js) which is due to the lower highest occupied molecular orbital (HOMO) level in DCJTB than that in CuPc. Also, the short circuit current density (JSC) is affected when the DCJTB layer becomes thicker, resulting from the high series resistance RsA due to the low charge carrier mobility of fluorescent red dye.展开更多
The performance of an organic photovoltaic (OPV) cell based on copper phthatocyanine CuPc/C60 with a tris- (8-hydroxyquinolinato) aluminum (Alq3) buffer layer has been investigated. It was found that the power c...The performance of an organic photovoltaic (OPV) cell based on copper phthatocyanine CuPc/C60 with a tris- (8-hydroxyquinolinato) aluminum (Alq3) buffer layer has been investigated. It was found that the power conversion efficiency of the device was 1.51% under illumination with an intensity of 100 mW/cm^2, which was limited by a squareroot dependence of the photocurrent on voltage. The photocurrent optical power density characteristics showed that the OPV cell had a significant space-charge limited photocurrent with a varied saturation voltage and a three quarters power dependence on optical power density. Also, the absorption spectrum was measured by a spectrophotometer, and the results showed that the additional Alq3 layer has a minor effect on photocurrent generation.展开更多
Organic photovoltaic(OPV)cells have demonstrated remarkable performance in small,spin-coated areas.Nevertheless significant challenges persist in the form of large efficiency losses due to the fact that the ideal morp...Organic photovoltaic(OPV)cells have demonstrated remarkable performance in small,spin-coated areas.Nevertheless significant challenges persist in the form of large efficiency losses due to the fact that the ideal morphology cannot be preserved in the transition of small-area cells to large-scale panels.Herein,the ternary strategy of incorporating the third component FTCC-Br into the active layer of PB2:BTP-eC9 is employed to improve absorption response,optimize morphology,and reduce charge recombination,leading to a power conversion efficiency(PCE)of 19.5%(certified as 19.1%by the National Institute of Metrology,China).Moreover,the addition of FTCC-Br can control the aggregation kinetics of the active layer during the film formation process,transferring the optimal morphology to the blade-coated large-area films.Based on the highly efficient ternary bulk heterojunction,the 50 cm^(2) OPVmodules exhibited a PCE of 15.2%with respect to the active area.Importantly,the ternary OPV cells retain 80%of its initial PCE after 4000 h under continuous illumination.Our work demonstrates that the addition of a third component has the potential to improve the efficiency and stability of large-area organic solar cells.展开更多
We demonstrate that power recycling is feasible by using a semi-transparent stripped Al electrode as interconnecting layer to merge a white organic light-emitting devices(WOLED) and an organic photovoltaic(OPV) cell.T...We demonstrate that power recycling is feasible by using a semi-transparent stripped Al electrode as interconnecting layer to merge a white organic light-emitting devices(WOLED) and an organic photovoltaic(OPV) cell.The device is called a PVOLED.It has a glass / ITO / CuPc / m-MTDATA ∶ V 2 O 5 / NPB / CBP ∶ FIrpic ∶ DCJTB / BPhen / LiF / Al / P3HT∶ PCBM / V 2 O 5 / Al structure.The power recycling efficiency of 10.133% is achieved under the WOLED of PVOLED operated at 9 V and at a brightness of 2 110 cd / m 2,when the conversion efficiency of OPV is 2.3%.We have found that the power recycling efficiency is decreased under high brightness and high applied voltage due to an increase input power of WOLED.High efficiency(18.3 cd / A) and high contrast ratio(9.3) were obtained at the device operated at 2 500 cd / m 2 under an ambient illumination of 24 000 lx.Reasonable white light emission with Commission Internationale De L'Eclairage(CIE) color coordinates of(0.32,0.44) at 20 mA / cm 2 and slight color shift occurred in spite of a high current density of 50 mA / cm 2.The proposed PVOLED is highly promising for use in outdoors display applications.展开更多
We have improved the photovoltaic performance of 2,4-bis[4-(N,N- diisobutylamino)-2,6-dihydroxyphenyl] squaraine:[6,6]-phenyl C71-butyric acid methyl ester (DIBSQ:PC71BM) organic photovoltaic (OPV) cells via i...We have improved the photovoltaic performance of 2,4-bis[4-(N,N- diisobutylamino)-2,6-dihydroxyphenyl] squaraine:[6,6]-phenyl C71-butyric acid methyl ester (DIBSQ:PC71BM) organic photovoltaic (OPV) cells via incorporating Liq-doped Bphen (Bphen-Liq) as a cathode buffer layer (CBL). Based on the Bphen-Liq CBL, a DIBSQ:PC71BM OPV cell possessed an optimal power conversion efficiency of 4.90%, which was 13% and 60% higher than those of the devices with neat Bphen as CBL and without CBL, respectively. The enhancement of the device performance could be attributed to the enhanced electron mobility and improved electrode/active layer contact and thus the improved photocurrent extraction by incorporating the Bphen-Liq CBL. Light-intensity dependent device performance analysis indicates that the incorporating of the Bphen-Liq CBL can remarkably improve the charge transport of the DIBSQ:PC71BM OPV cell and thus decrease the recombination losses of the device, resulting in enhanced device performance. Our finding indicates that the doped Bphen-Liq CBL has great potential for high-performance solution-processed small-molecule OPVs.展开更多
A series of organic photovoltaic (PV) cells in which the electron acceptor and donor are gadolinium (dibenzoylmethanato)_3(bathophenanthroline) [Gd(DBM)_3bath] and N,N′-diphenyl-N,N′bis(3-methylphenyl)-1,1′-dipheny...A series of organic photovoltaic (PV) cells in which the electron acceptor and donor are gadolinium (dibenzoylmethanato)_3(bathophenanthroline) [Gd(DBM)_3bath] and N,N′-diphenyl-N,N′bis(3-methylphenyl)-1,1′-diphenyl-4,4′-diamine [TPD], respectively, were fabricated. Although TPD acts as an active layer in the bilayered cells, insertion of a Gd-complex film between TPD and the alloy cathode is necessary for efficient carrier photogeneration. Open-circuit voltage of 3.2 V was obtained due to efficient exciton dissociation near the interface between Gd(DBM)_3bath and TPD. By incorporating an ultrathin mixed layer of Gd-complex and TPD, external quantum efficiency is improved significantly. Photovoltaic performance of the devices has a common origin, exciplex formation, which results in broadband emission during both photoluminescent and the electroluminescent processes.展开更多
The application of organic photovoltaic(OPV)cells to drive off-grid microelectronic devices under indoor light has attracted broad attention.As organic semiconductors intrinsically have less ordered intermolecular pac...The application of organic photovoltaic(OPV)cells to drive off-grid microelectronic devices under indoor light has attracted broad attention.As organic semiconductors intrinsically have less ordered intermolecular packing than inorganic materials,the relatively larger energetic disorder is one of the main results that limit the photovoltaic efficiency of the OPV cells at low carrier density.Here,we optimize the alkyl chains of non-fullerene acceptors to get suppressed energetic disorder.We find the optimal acceptor DTz-R1 with the shortest alkyl chain has the strongest crystalline property and lowest energetic disorder.As a result,over 26%efficiency is recorded for the 1 cm^(2) OPV cells under a light-emitting diode illumination of 500 lux.We also fabricate a 100 cm^(2) cell device and get a PCE of 23.0%,which is an outstanding value for large-area OPV cells.These results suggest that modulation of the energetic disorder is of great importance for further improving the efficiency of OPV cells,especially for indoor applications.展开更多
Cyano substitution is vital to the molecular design of polymer semiconductors toward highly efficient organic solar cells.However,how regioselectivity impacts relevant optoelectronic properties in cyano-substituted bi...Cyano substitution is vital to the molecular design of polymer semiconductors toward highly efficient organic solar cells.However,how regioselectivity impacts relevant optoelectronic properties in cyano-substituted bithiophene systems remain poorly understood.Three regioisomeric cyano-functionalized dialkoxybithiophenes BT_(HH),BT_(HT),and BT_(TT) with headto-head,head-to-tail,and tail-to-tail linkage,respectively,were synthesized and characterized in this work.The resulting polymer semiconductors(PBDTBTs)based on these building blocks were prepared accordingly.The regiochemistry and property relationships of PBDTBTs were investigated in detail.The BTHH moiety has a higher torsional barrier than the analogs BT_(HT) and BT_(TT),and the regiochemistry of dialkoxybithiophenes leads to fine modulation in the optoelectronic properties of these polymers,such as optical absorption,band gap,and energy levels of frontier molecular orbitals.Organic field-effect transistors based on PBDTBT_(HH) had higher hole mobility(4.4×10^(-3) cm^(2)/(V·s))than those(ca.10^(-4) cm^(2)/(V·s))of the other two polymer analogs.Significantly different short-circuit current densities and fill factors were obtained in polymer solar cells using PBDTBTs as the electron donors.Such difference was probed in greater detail by performing space-charge-limited current mobility,thin-film morphology,and transient photocurrent/photovoltage characterizations.The findings highlight that the BTHH unit is a promising building block for the construction of polymer donors for highperformance organic photovoltaic cells.展开更多
Minimizing energy loss(E_(loss))plays a key role in improving the power conversion efficiencies(PCEs)of organic solar cells(OSCs).Here,to reveal the feasibility of the asymmetric molecular strategy in designing high-e...Minimizing energy loss(E_(loss))plays a key role in improving the power conversion efficiencies(PCEs)of organic solar cells(OSCs).Here,to reveal the feasibility of the asymmetric molecular strategy in designing high-efficiency and low E_(loss)s OSC materials,we adopt the alkyl-alkoxy modification to design an asymmetric non-fullerene acceptor(NFA)named OC8-4F,where its symmetric alkyl-and alkoxy-substituted counterparties(2OC8-4F,eC9-4F)are also prepared.The results suggest that the introduction of a symmetric alkoxy at the edge of eC9-4F can effectively decrease the lowest unoccupied molecular orbit level without greatly changing the highest occupied molecular orbit level,leading to a mediated bandgap.In the devices,the OC8-4F possesses well-balanced charge generation and E_(loss),giving the highest PCE of 18%.Our results imply that finely tuning the asymmetric structure can be used as an effective molecular design strategy to improve the photovoltaic performance of OSCs.展开更多
基金Project supported by the Special Funds for the Development of Strategic Emerging Industries in Shenzhen City,China(Grant No.JCYJ20120830154526537)Start-up Funding of the South University of Science and Technology of China,and the Strategic Research Grant of the City University of Hong Kong(Grant No.7002724)
文摘Efficient heterojunction organic photovoltaic (OPV) cells are fabricated based on copper tetra-methyl phthalocyanine (CuMePc) as donor and fullerene (C60) as acceptor. The power conversion efficiency of CuMePc/C60 OPV cell (2.52%) is increased by 88% compared with that of the non-peripheral substituted copper phthalocyanine (CuPc)/C60 OPV cell (1.34%). The introduction of methyl substituent leads to stronger π–π interaction of CuMePc (~ 3.5 ?) than that of CuPc (~ 3.8 ?). The efficiency improvement is attributed to the enhanced carrier mobility of CuMePc thin film (1.1×10-3 cm2/V·s) and better film morphology by introducing methyl groups into the periphery of CuPc molecule.
文摘Organic photovoltaic cells have been fabricated using copper phthalocyanine CuPc as electron donor and C60 or PCBM as electron acceptor. We have investigated the I-V measurements of two different structures: ITO/PEDOT: PSS/(CuPc:C60 or CuPc:PCBM)/BCP/Al. We have observed that the substitution of PCBM by C60 scales up the photocurrent and the efficiency of the devices. As for the open-circuit voltage and the fill factor, we have seen that Voc and FF depend on the energy difference between the highest occupied molecular orbital (HOMO) of CuPc and the lowest unoccupied molecular orbital (LUMO)of C60 or PCBM.
基金Project partially supported by the National Natural Science Foundation of China(NNSFC)(Grant Nos.60736005 and 60425101-1)the Foundation for Innovative Research Groups of the NNSFC(Grant No.60721001)+3 种基金the Research Fund for the Dectoral Program of Higher Education(RFDP)(Grant No.20090185110020)the Program for New Century Excellent Talents in University,China(Grant No.NCET-06-0812)the Scientific Research Foundation for Returned Overseas Chinese Scholars,State Education Ministry(Grant No.GGRYJJ08-05)the Young Excellence Project of Sichuan Province,China(Grant No.09ZQ026-074)
文摘The influence of an ultrathin 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) fluorescent dye layer at donor/acceptor heterojunction on the performance of small-molecule organic photovoltaic (OPV) cell is studied. The structure of OPV cell is of indium-tin oxide (ITO)/copper phthalocyanine (CuPc)/DCJTB/fullerene (C60)/bathophenantbroline (Bphen)/Ag. The results show that open circuit voltage (Voc) increases to 0.57 V as the film thickness of DCJTB layer increases from 0.2 to 2.0 nm. By using an equivalent circuit model, the enhancement of VOC is found to be attributed to the reduced reverse saturation current density (Js) which is due to the lower highest occupied molecular orbital (HOMO) level in DCJTB than that in CuPc. Also, the short circuit current density (JSC) is affected when the DCJTB layer becomes thicker, resulting from the high series resistance RsA due to the low charge carrier mobility of fluorescent red dye.
基金Project supported by the National Natural Science Foundation of China (NSFC) (Grant Nos. 60736005 and 60425101-1)the Foundation for Innovative Research Groups of the NSFC (Grant No. 60721001),Provincial Project (Grant No. 9140A02060609DZ0208)+1 种基金Program for New Century Excellent Talents in University (Grant No. NCET-06-0812),SRF for ROCS,SEM (Grant No. GGRYJJ08-05)Young Excellent Project of Sichuan Province (Grant No. 09ZQ026-074)
文摘The performance of an organic photovoltaic (OPV) cell based on copper phthatocyanine CuPc/C60 with a tris- (8-hydroxyquinolinato) aluminum (Alq3) buffer layer has been investigated. It was found that the power conversion efficiency of the device was 1.51% under illumination with an intensity of 100 mW/cm^2, which was limited by a squareroot dependence of the photocurrent on voltage. The photocurrent optical power density characteristics showed that the OPV cell had a significant space-charge limited photocurrent with a varied saturation voltage and a three quarters power dependence on optical power density. Also, the absorption spectrum was measured by a spectrophotometer, and the results showed that the additional Alq3 layer has a minor effect on photocurrent generation.
基金the National Natural Science Foundation of China(NSFC,grant nos.21835006 and 51961135103)the Bureau of International Cooperation Chinese Academy of Sciences(grant no.121111KYSB20200043)+1 种基金the financial support from China Postdoctoral Science Foundation(grant no.2022M723199)the Beijing National Laboratory for Molecular Sciences Junior Fellow.
文摘Organic photovoltaic(OPV)cells have demonstrated remarkable performance in small,spin-coated areas.Nevertheless significant challenges persist in the form of large efficiency losses due to the fact that the ideal morphology cannot be preserved in the transition of small-area cells to large-scale panels.Herein,the ternary strategy of incorporating the third component FTCC-Br into the active layer of PB2:BTP-eC9 is employed to improve absorption response,optimize morphology,and reduce charge recombination,leading to a power conversion efficiency(PCE)of 19.5%(certified as 19.1%by the National Institute of Metrology,China).Moreover,the addition of FTCC-Br can control the aggregation kinetics of the active layer during the film formation process,transferring the optimal morphology to the blade-coated large-area films.Based on the highly efficient ternary bulk heterojunction,the 50 cm^(2) OPVmodules exhibited a PCE of 15.2%with respect to the active area.Importantly,the ternary OPV cells retain 80%of its initial PCE after 4000 h under continuous illumination.Our work demonstrates that the addition of a third component has the potential to improve the efficiency and stability of large-area organic solar cells.
基金Project supported by NSC(98-2221-E-214-003-MY3 and ISU99-01-06)
文摘We demonstrate that power recycling is feasible by using a semi-transparent stripped Al electrode as interconnecting layer to merge a white organic light-emitting devices(WOLED) and an organic photovoltaic(OPV) cell.The device is called a PVOLED.It has a glass / ITO / CuPc / m-MTDATA ∶ V 2 O 5 / NPB / CBP ∶ FIrpic ∶ DCJTB / BPhen / LiF / Al / P3HT∶ PCBM / V 2 O 5 / Al structure.The power recycling efficiency of 10.133% is achieved under the WOLED of PVOLED operated at 9 V and at a brightness of 2 110 cd / m 2,when the conversion efficiency of OPV is 2.3%.We have found that the power recycling efficiency is decreased under high brightness and high applied voltage due to an increase input power of WOLED.High efficiency(18.3 cd / A) and high contrast ratio(9.3) were obtained at the device operated at 2 500 cd / m 2 under an ambient illumination of 24 000 lx.Reasonable white light emission with Commission Internationale De L'Eclairage(CIE) color coordinates of(0.32,0.44) at 20 mA / cm 2 and slight color shift occurred in spite of a high current density of 50 mA / cm 2.The proposed PVOLED is highly promising for use in outdoors display applications.
基金Acknowledgements This work was financially supported by the National Natural Science Foundation of China (Grant No. 61604093), the Natural Science Foundation of Shanghai (16ZR1411000), the Shanghai Pujiang Program (16PJ1403300), and the Shanghai University Young Teacher Training Program (ZZSD 15049).
文摘We have improved the photovoltaic performance of 2,4-bis[4-(N,N- diisobutylamino)-2,6-dihydroxyphenyl] squaraine:[6,6]-phenyl C71-butyric acid methyl ester (DIBSQ:PC71BM) organic photovoltaic (OPV) cells via incorporating Liq-doped Bphen (Bphen-Liq) as a cathode buffer layer (CBL). Based on the Bphen-Liq CBL, a DIBSQ:PC71BM OPV cell possessed an optimal power conversion efficiency of 4.90%, which was 13% and 60% higher than those of the devices with neat Bphen as CBL and without CBL, respectively. The enhancement of the device performance could be attributed to the enhanced electron mobility and improved electrode/active layer contact and thus the improved photocurrent extraction by incorporating the Bphen-Liq CBL. Light-intensity dependent device performance analysis indicates that the incorporating of the Bphen-Liq CBL can remarkably improve the charge transport of the DIBSQ:PC71BM OPV cell and thus decrease the recombination losses of the device, resulting in enhanced device performance. Our finding indicates that the doped Bphen-Liq CBL has great potential for high-performance solution-processed small-molecule OPVs.
文摘A series of organic photovoltaic (PV) cells in which the electron acceptor and donor are gadolinium (dibenzoylmethanato)_3(bathophenanthroline) [Gd(DBM)_3bath] and N,N′-diphenyl-N,N′bis(3-methylphenyl)-1,1′-diphenyl-4,4′-diamine [TPD], respectively, were fabricated. Although TPD acts as an active layer in the bilayered cells, insertion of a Gd-complex film between TPD and the alloy cathode is necessary for efficient carrier photogeneration. Open-circuit voltage of 3.2 V was obtained due to efficient exciton dissociation near the interface between Gd(DBM)_3bath and TPD. By incorporating an ultrathin mixed layer of Gd-complex and TPD, external quantum efficiency is improved significantly. Photovoltaic performance of the devices has a common origin, exciplex formation, which results in broadband emission during both photoluminescent and the electroluminescent processes.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.52003275,22075301,22122905 and 52120105005)J.H.Hou was supported by the Key Research Program of the Chinese Academy of Sciences(No.XDPB13)the Bureau of International Cooperation Chinese Academy of Sciences(No.121111KYSB20200043).
文摘The application of organic photovoltaic(OPV)cells to drive off-grid microelectronic devices under indoor light has attracted broad attention.As organic semiconductors intrinsically have less ordered intermolecular packing than inorganic materials,the relatively larger energetic disorder is one of the main results that limit the photovoltaic efficiency of the OPV cells at low carrier density.Here,we optimize the alkyl chains of non-fullerene acceptors to get suppressed energetic disorder.We find the optimal acceptor DTz-R1 with the shortest alkyl chain has the strongest crystalline property and lowest energetic disorder.As a result,over 26%efficiency is recorded for the 1 cm^(2) OPV cells under a light-emitting diode illumination of 500 lux.We also fabricate a 100 cm^(2) cell device and get a PCE of 23.0%,which is an outstanding value for large-area OPV cells.These results suggest that modulation of the energetic disorder is of great importance for further improving the efficiency of OPV cells,especially for indoor applications.
基金supported by the National Natural Science Foundation of China(Nos.52173172,52173171,and 21801124)the Natural Science Foundation for Distinguished Young Scholars of Guangdong Province(2021B1515020027)+6 种基金Guangdong Basic and Applied Basic Research Foundation(2021A1515110892)China Postdoctoral Science Foundation(2021M700062)the Shenzhen Science and Technology Innovation Commission(JCYJ202103243104813035 and JCYJ20180504165709042)the Open Fund of the State Key Laboratory of Luminescent Materials and Devices(South China University of Technology)financial support from the Songshan Lake Materials Laboratory(2021SLABFK03)financial support from the NRF of Korea(2016M1A2A2940911,2017K2A9A2A12000315)supported by the Center for Computational Science and Engineering of Southern University of Science and Technology。
文摘Cyano substitution is vital to the molecular design of polymer semiconductors toward highly efficient organic solar cells.However,how regioselectivity impacts relevant optoelectronic properties in cyano-substituted bithiophene systems remain poorly understood.Three regioisomeric cyano-functionalized dialkoxybithiophenes BT_(HH),BT_(HT),and BT_(TT) with headto-head,head-to-tail,and tail-to-tail linkage,respectively,were synthesized and characterized in this work.The resulting polymer semiconductors(PBDTBTs)based on these building blocks were prepared accordingly.The regiochemistry and property relationships of PBDTBTs were investigated in detail.The BTHH moiety has a higher torsional barrier than the analogs BT_(HT) and BT_(TT),and the regiochemistry of dialkoxybithiophenes leads to fine modulation in the optoelectronic properties of these polymers,such as optical absorption,band gap,and energy levels of frontier molecular orbitals.Organic field-effect transistors based on PBDTBT_(HH) had higher hole mobility(4.4×10^(-3) cm^(2)/(V·s))than those(ca.10^(-4) cm^(2)/(V·s))of the other two polymer analogs.Significantly different short-circuit current densities and fill factors were obtained in polymer solar cells using PBDTBTs as the electron donors.Such difference was probed in greater detail by performing space-charge-limited current mobility,thin-film morphology,and transient photocurrent/photovoltage characterizations.The findings highlight that the BTHH unit is a promising building block for the construction of polymer donors for highperformance organic photovoltaic cells.
基金support from the National Natural Science Foundation of China(Nos.22122905,22075301,21835006)J.H.is supported by Beijing National Laboratory for Molecular Sciences(BNLMS-CXXM-201903)the"Dual Carbon"Science and Technology Innovation of Jiangsu province(Industrial Prospect and Key Technology Research program)(BE2022021).
文摘Minimizing energy loss(E_(loss))plays a key role in improving the power conversion efficiencies(PCEs)of organic solar cells(OSCs).Here,to reveal the feasibility of the asymmetric molecular strategy in designing high-efficiency and low E_(loss)s OSC materials,we adopt the alkyl-alkoxy modification to design an asymmetric non-fullerene acceptor(NFA)named OC8-4F,where its symmetric alkyl-and alkoxy-substituted counterparties(2OC8-4F,eC9-4F)are also prepared.The results suggest that the introduction of a symmetric alkoxy at the edge of eC9-4F can effectively decrease the lowest unoccupied molecular orbit level without greatly changing the highest occupied molecular orbit level,leading to a mediated bandgap.In the devices,the OC8-4F possesses well-balanced charge generation and E_(loss),giving the highest PCE of 18%.Our results imply that finely tuning the asymmetric structure can be used as an effective molecular design strategy to improve the photovoltaic performance of OSCs.