Recently,the rapid development of non-fullerene acceptors(NFAs)has laid the foundation for performance improvements in near-infrared(NIR)organic photodetectors(OPDs).However,reducing the bandgap of NFAs to achieve str...Recently,the rapid development of non-fullerene acceptors(NFAs)has laid the foundation for performance improvements in near-infrared(NIR)organic photodetectors(OPDs).However,reducing the bandgap of NFAs to achieve strong absorption in the shorter-wave region usually leads to increased dark current density(J_(d))and decreased responsivity(R),severely limiting the detectivity(D*)of NIR-OPDs.To date,it remains challenging to manipulate the J_(d) of NIR-OPDs through rational structure engineering of NFAs.Herein,three NIR-NFAs,namely bis(2-decyltetradecyl)4,4′-(2′,7′-di-tert-butylspiro[cyclopenta[2,1-b:3,4-b′]dithiophene-4,9′-fluorene]-2,6-diyl)bis(6-(((Z)-1-(dicyanomethylene)-5,6-difluoro-3-oxo-1,3-dihydro-2H-inden-2-ylidene)methyl)thieno[3,4-b]thiophene-2-carboxylate)(TSIC-4F),bis(2-decyltetradecyl)6,6′-(2′,7′-di-tert-butylspiro[cyclopenta[2,1-b:3,4-b′]dithiophene-4,9′-fluorene]-2,6-diyl)bis(4-(((Z)-1-(dicyanomethylene)-5,6-difluoro-3-oxo-1,3-dihydro-2H-inden-2-ylidene)methyl)thieno[3,4-b]thiophene-2-carboxylate)(STIC-4F),and 2,2′-((2Z,2′Z)-(((2′,7′-di-tert-butylspiro[cyclopenta[2,1-b:3,4-b′]dithiophene-4,9′-fluorene]-2,6-diyl)bis(2,3-bis(5-(2-butyloctyl)thiophen-2-yl)thieno[3,4-b]pyrazine-7,5-diyl))bis(metha-neylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(TPIC-4F),were designed using the thieno[3,4-b]thiophene(TT)and thieno[3,4-b]pyrazine(TPy)derivatives as theπ-bridge.Owing to the intramolecular S-S and S-N interactions,STIC-4F and TPIC-4F exhibited smaller backbone distortions than TSIC-4F.A significantly red-shifted absorption with a peak at 1015 nm was observed in TPIC-4F film,larger than that(ca.960 nm)for TSIC-4F and STIC-4F films.Moreover,OPDs operating in a photovoltaic mode were successfully fabricated,and TPIC-4F-based OPDs achieved the lowest J_(d) of 3.18×10^(-8) A/cm^(2) at-0.1 V.Impressively,although TPIC-4F-based OPDs exhibited the lowest R,higher shot-noise-limited specific detectivity(D_(sh)*)in 1000-1200 nm could be achieved due to its lowest J_(d).This study underscored the effectiveness of optimizing theπ-bridge structure of NFAs to suppress J_(d),ultimately attaining higher D_(sh)*in the NIR region.展开更多
All-small-molecule organic solar cells (ASM OSCs) are promising for commercial application due to the well-defined chemical structures, convenient purifying process and low batch-to-batch variation. However, the simil...All-small-molecule organic solar cells (ASM OSCs) are promising for commercial application due to the well-defined chemical structures, convenient purifying process and low batch-to-batch variation. However, the similarity of molecule structures between small molecule donors and acceptors makes a hard regulation of their blend morphology, which will limit the efficiency.展开更多
Reducing energy loss(V_(loss))is one of the most crucial challenges in organic photovoltaic cells.The V_(loss),determined by the differences between the optical band gap(E_(g))of the active layer material and the open...Reducing energy loss(V_(loss))is one of the most crucial challenges in organic photovoltaic cells.The V_(loss),determined by the differences between the optical band gap(E_(g))of the active layer material and the open-circuit voltage(V_(oc))of the device,is generally alleviated by lowering the energy difference between the lowest unoccupied molecular orbital(LUMO)and highest occupied molecular orbital(HOMO)level of the donor(D)and acceptor(A).In this work,we synthesized two A-π-D-π-A-type small-molecule donors(SMDs)SM-benzotriazole(BTz)-1 and SM-BTz-2 by introducing a BTzπ-bridge unit and terminal regulation.The BTzπ-bridge unit significantly lowers the HOMO energy level of SMDs,resulting in high V_(oc)and high mobility,achieving a balance of low energy loss(<0.5 eV)and high efficiency.Ultimately,the organic solar cells based on SM-BTz-2 as the donor and Y6 as the acceptor obtain a high V_(oc)of 0.91 V,J_(sc) of 22.8 mA cm^(−2),fill factor of 68%,and power conversion efficiency(PCE)of 14.12%,which is one of the highest efficiencies based on the SMDs with triazoleπ-bridges to date.What’s more,the BTzπ-bridge unit is a potential unit that can improve mobility and reduce energy loss.展开更多
A rational design of efficient low-band-gap non-fullerene acceptors(NFAs)for high-performance organic solar cells(OSCs)remains challenging;the main constraint being the decrease in the energy level of the lowest unocc...A rational design of efficient low-band-gap non-fullerene acceptors(NFAs)for high-performance organic solar cells(OSCs)remains challenging;the main constraint being the decrease in the energy level of the lowest unoccupied molecular orbitals(LUMOs)as the bandgap of A-D-A-type NFAs decrease.Therefore,the short current density(J_(sc))and open-circuit voltage(V_(oc))result in a trade-off relationship,making it difficult to obtain efficient OSCs.Herein,three NFAs(IFL-ED-4 F,IDT-ED-4 F,and IDTT-ED-2 F)were synthesized to address the above-mentioned issue by introducing 3,4-ethylenedioxythiophene(EDOT)as aπ-bridge.These NFAs exhibit relatively low bandgaps(1.67,1.42,and 1.49 eV,respectively)and upshifted LUMO levels(-3.88,-3.84,and-3.81 eV,respectively)compared with most reported low-band-gap NFAs.Consequently,the photovoltaic devices based on IDT-ED-4 F blended with a PBDB-T donor polymer showed the best power conversion efficiency(PCE)of 10.4%with a high J_(sc) of 22.1 mA cm^(-2) and Voc of 0.884 V among the examined NFAs.In contrast,IDTT-ED-4 F,which was designed with an asymmetric structure of the D-p-A type,showed the lowest efficiency of 1.5%owing to the poor morphology and charge transport properties of the binary blend.However,when this was introduced as the third component of the PM6:BTP-BO-4 Cl,complementary absorption and cascade energy-level alignment between the two substances could be achieved.Surprisingly,the IDTT-ED-4 F-based ternary blend device not only improved the Jscand Voc,but also achieved a PCE of 15.2%,which is approximately 5.3%higher than that of the reference device with a minimized energy loss of 0.488 eV.In addition,the universality of IDTT-ED-2 F as a third component was effectively demonstrated in other photoactive systems,specifically,PM6:BTPe C9 and PTB7-Th:IEICO-4 F.This work facilitates a better understanding of the structure–property relationship for utilizing efficient EDOT-bridged NFAs in high-performance OSC applications.展开更多
Selection of the strategically substituted alkyl chains has a significant effect to modulate the physical properties of conjugated polymers,electro-optical characteristics,and active layer morphology of the correspond...Selection of the strategically substituted alkyl chains has a significant effect to modulate the physical properties of conjugated polymers,electro-optical characteristics,and active layer morphology of the corresponding polymer solar cells(PSCs).Herein,we systematically synthesized three dibenzo[a,c]phenazine based D-π-A donor polymers named PBP-C0,PBP-C8,and PBP-C6 with different alkyl substitutions on thiopheneπ-bridges,without alkyl,2-ethylhexyl and n-hexyl groups,respectively.The absence of the alkyl chain(PBP-C0)on theπ-bridge caused poor solubility and unfavorable miscibility with the Y5 acceptor,leading to the lower photovoltaic performance.The bulky alkyl chain of 2-ethylhexyl on theπ-bridge group caused the twisting of PBP-C8 conjugated backbone,which limits the charge transport and also compromises the photovoltaic performance.In contrast,the PBP-C6-with flexible linear alkyl chains has almost planar curvature geometry resulting in the small uniform domain size and appropriate phase separation in the blend film morphology.These favorable properties enhanced the exciton generation to dissociation,charge carrier mobility,and also lowered the charge recombination.Among three polymers,PBP-C6-based devices exhibit the best PCE of 11.60%.From these results,thiopheneπ-bridge alkyl substitution demonstrated an important strategy to adjust energy level,absorption,and phase separation morphology to enhance the photovoltaic performance of the PSCs.展开更多
Dye-sensitized solar cells(DSSCs)have gained critical importance as a leading emerging photovoltaic technology for low-cost power generation due to their simple production,light weight,applicability to the development...Dye-sensitized solar cells(DSSCs)have gained critical importance as a leading emerging photovoltaic technology for low-cost power generation due to their simple production,light weight,applicability to the development of flexible photovoltaic devices,and use of abundant and inexpensive materials,including advantageous metal-free organic dyes.In this context,as a continuation of our work on DSSCs,a theoretical examination using density functional theory(DFT)and time-dependent density functional theory(TD-DFT)was conducted to evaluate the photovoltaic performance of eight new organic dyes.Each dye contains an electron donor group((E)-2-(2-(thiophen-3-yl)vinyl)-1,1′-bipyrrole),an electron acceptor group(cyanoacrylic acid(CCA)),and four auxiliary donor/acceptor groups,i.e.,3,4-ethylenedioxythiophene(EDOT),furan/benzothiadiazole(BTZ),diketopyrrolopyrrole(DPP)linked toπ-conjugated bridges such as styrene or thiophene.We calculated several parameters for each dye,including EHOMO,ELUMO,Egap,𝜆max,Eex,pen-circuit photovoltage(VOC),light harvesting efficiency(LHE),regeneration driving force(ΔGreg),electron injection driving force(ΔGinject),and excitation lifetime(𝜏)to determine the photovoltaic efficiency of each dye.The results showed that the new dyes exhibited good performance and remarkable energy-conversion efficiencies.Additionally,all investigated dyes posed as promising candidates for the generation of effective DSSC sensitizers,particularly M6,which contained a styrene-linked EDOT auxiliary donor group.展开更多
Main observation and conclusion Recently,the asymmetric nonfullerene acceptors(NFAs)with acceptor-donor-acceptor(A-D-A)structure have been developed rapidly,especially for the modification of asymmetric core,asymmetri...Main observation and conclusion Recently,the asymmetric nonfullerene acceptors(NFAs)with acceptor-donor-acceptor(A-D-A)structure have been developed rapidly,especially for the modification of asymmetric core,asymmetric side chains and asymmetric end groups.In this work,a novel asymmetric A-D-π-A type NFA with a noncovalently fused-ring core named PIST-4F is synthesized,containing an indacenodithieno[3,2-b]dithiophene(IDT),two strong electron-withdrawing end groups and an alkylthio-substituted thiopheneπ-bridge.Benefiting from the S···S noncovalent interaction between the sulfur atom onπ-bridge and the adjacent thiophene in IDT,the PIST-4F presents nearly planar geometry and extended conjugated area,resulting in the optimized electronic properties,charge transport,and film morphology compared to the symmetric NFA PI-4F.As a result,PM6:PIST-4F-based devices achieve a higher power conversion efficiency(PCE)of 13.8%,while the PM6:PI-4F-based devices only show a PCE of 7.1%.Notably,the PM6:PIST-4F-based devices processed with nonhalogen solvent toluene exhibit an excellent PCE as high as 13.1%.These results indicate that PIST-4F is an effective acceptor for high-efficiency organic solar cells.展开更多
Benzo[1,2-b:4,5-b′]dithiophene(BDT) has been widely used to construct donor-acceptor(D-A) copolymers in organic solar cells(OSCs). However, benzo[1,2-b:4,5-b′]difuran(BDF), an analogue of BDT, has received less atte...Benzo[1,2-b:4,5-b′]dithiophene(BDT) has been widely used to construct donor-acceptor(D-A) copolymers in organic solar cells(OSCs). However, benzo[1,2-b:4,5-b′]difuran(BDF), an analogue of BDT, has received less attention than BDT. The photovoltaic performance of BDF copolymers has lagged behind that of BDT copolymers. Here, we designed and synthesized two BDF copolymers, PBF1-C and PBF1-C-2Cl. PBF1-C-2Cl, which is composed of BDF and benzo[1,2-c:4,5-c′]dithiophene-4,8-dione connected by a chlorinated thiophene π-bridge, displays a low-lying highest occupied molecular orbital energy level,which helps in yielding a high open-circuit voltage(Voc) in OSCs. As a result, when blended with Y6, PBF1-C-2Cl-based devices showed a high Voc of 0.83 V and a power conversion efficiency(PCE) of 13.10%. To the best of our knowledge, the PCE of 13.10% is among the highest efficiency values for OSCs based on BDF copolymers.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U21A6002,51933003,52203355)the Basic and Applied Basic Research Foundation of Guangdong Province,China(Nos.2019B030302007,2023A1515012293)the Guangzhou Science and Technology Plan Project,China(No.2023A04J0970).
文摘Recently,the rapid development of non-fullerene acceptors(NFAs)has laid the foundation for performance improvements in near-infrared(NIR)organic photodetectors(OPDs).However,reducing the bandgap of NFAs to achieve strong absorption in the shorter-wave region usually leads to increased dark current density(J_(d))and decreased responsivity(R),severely limiting the detectivity(D*)of NIR-OPDs.To date,it remains challenging to manipulate the J_(d) of NIR-OPDs through rational structure engineering of NFAs.Herein,three NIR-NFAs,namely bis(2-decyltetradecyl)4,4′-(2′,7′-di-tert-butylspiro[cyclopenta[2,1-b:3,4-b′]dithiophene-4,9′-fluorene]-2,6-diyl)bis(6-(((Z)-1-(dicyanomethylene)-5,6-difluoro-3-oxo-1,3-dihydro-2H-inden-2-ylidene)methyl)thieno[3,4-b]thiophene-2-carboxylate)(TSIC-4F),bis(2-decyltetradecyl)6,6′-(2′,7′-di-tert-butylspiro[cyclopenta[2,1-b:3,4-b′]dithiophene-4,9′-fluorene]-2,6-diyl)bis(4-(((Z)-1-(dicyanomethylene)-5,6-difluoro-3-oxo-1,3-dihydro-2H-inden-2-ylidene)methyl)thieno[3,4-b]thiophene-2-carboxylate)(STIC-4F),and 2,2′-((2Z,2′Z)-(((2′,7′-di-tert-butylspiro[cyclopenta[2,1-b:3,4-b′]dithiophene-4,9′-fluorene]-2,6-diyl)bis(2,3-bis(5-(2-butyloctyl)thiophen-2-yl)thieno[3,4-b]pyrazine-7,5-diyl))bis(metha-neylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(TPIC-4F),were designed using the thieno[3,4-b]thiophene(TT)and thieno[3,4-b]pyrazine(TPy)derivatives as theπ-bridge.Owing to the intramolecular S-S and S-N interactions,STIC-4F and TPIC-4F exhibited smaller backbone distortions than TSIC-4F.A significantly red-shifted absorption with a peak at 1015 nm was observed in TPIC-4F film,larger than that(ca.960 nm)for TSIC-4F and STIC-4F films.Moreover,OPDs operating in a photovoltaic mode were successfully fabricated,and TPIC-4F-based OPDs achieved the lowest J_(d) of 3.18×10^(-8) A/cm^(2) at-0.1 V.Impressively,although TPIC-4F-based OPDs exhibited the lowest R,higher shot-noise-limited specific detectivity(D_(sh)*)in 1000-1200 nm could be achieved due to its lowest J_(d).This study underscored the effectiveness of optimizing theπ-bridge structure of NFAs to suppress J_(d),ultimately attaining higher D_(sh)*in the NIR region.
基金The authors thank the National Natural Science Foundation of China(52103221,52172048)the Shandong Provincial Natural Science Foundation(ZR2021QB179,ZR2021QB024,ZR2021ZD06)the Fundamental Research Funds of Shandong University.
文摘All-small-molecule organic solar cells (ASM OSCs) are promising for commercial application due to the well-defined chemical structures, convenient purifying process and low batch-to-batch variation. However, the similarity of molecule structures between small molecule donors and acceptors makes a hard regulation of their blend morphology, which will limit the efficiency.
基金the National Key Research and Development Program of China(2019YFA0705900)the National Natural Science Foundation of China(51820105003,21734008,61904181,52173188 and 52103243)+1 种基金the Key Research Program of the Chinese Academy of Sciences(XDPB13)the Basic and Applied Basic Research Major Program of Guangdong Province(2019B030302007).
文摘Reducing energy loss(V_(loss))is one of the most crucial challenges in organic photovoltaic cells.The V_(loss),determined by the differences between the optical band gap(E_(g))of the active layer material and the open-circuit voltage(V_(oc))of the device,is generally alleviated by lowering the energy difference between the lowest unoccupied molecular orbital(LUMO)and highest occupied molecular orbital(HOMO)level of the donor(D)and acceptor(A).In this work,we synthesized two A-π-D-π-A-type small-molecule donors(SMDs)SM-benzotriazole(BTz)-1 and SM-BTz-2 by introducing a BTzπ-bridge unit and terminal regulation.The BTzπ-bridge unit significantly lowers the HOMO energy level of SMDs,resulting in high V_(oc)and high mobility,achieving a balance of low energy loss(<0.5 eV)and high efficiency.Ultimately,the organic solar cells based on SM-BTz-2 as the donor and Y6 as the acceptor obtain a high V_(oc)of 0.91 V,J_(sc) of 22.8 mA cm^(−2),fill factor of 68%,and power conversion efficiency(PCE)of 14.12%,which is one of the highest efficiencies based on the SMDs with triazoleπ-bridges to date.What’s more,the BTzπ-bridge unit is a potential unit that can improve mobility and reduce energy loss.
基金supported by the KU Research Professor Program of Konkuk Universitythe Korea Institute of Energy Technology Evaluation and Planning (KETEP)+1 种基金the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20193091010110)a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. 2020R1A2C201091611)。
文摘A rational design of efficient low-band-gap non-fullerene acceptors(NFAs)for high-performance organic solar cells(OSCs)remains challenging;the main constraint being the decrease in the energy level of the lowest unoccupied molecular orbitals(LUMOs)as the bandgap of A-D-A-type NFAs decrease.Therefore,the short current density(J_(sc))and open-circuit voltage(V_(oc))result in a trade-off relationship,making it difficult to obtain efficient OSCs.Herein,three NFAs(IFL-ED-4 F,IDT-ED-4 F,and IDTT-ED-2 F)were synthesized to address the above-mentioned issue by introducing 3,4-ethylenedioxythiophene(EDOT)as aπ-bridge.These NFAs exhibit relatively low bandgaps(1.67,1.42,and 1.49 eV,respectively)and upshifted LUMO levels(-3.88,-3.84,and-3.81 eV,respectively)compared with most reported low-band-gap NFAs.Consequently,the photovoltaic devices based on IDT-ED-4 F blended with a PBDB-T donor polymer showed the best power conversion efficiency(PCE)of 10.4%with a high J_(sc) of 22.1 mA cm^(-2) and Voc of 0.884 V among the examined NFAs.In contrast,IDTT-ED-4 F,which was designed with an asymmetric structure of the D-p-A type,showed the lowest efficiency of 1.5%owing to the poor morphology and charge transport properties of the binary blend.However,when this was introduced as the third component of the PM6:BTP-BO-4 Cl,complementary absorption and cascade energy-level alignment between the two substances could be achieved.Surprisingly,the IDTT-ED-4 F-based ternary blend device not only improved the Jscand Voc,but also achieved a PCE of 15.2%,which is approximately 5.3%higher than that of the reference device with a minimized energy loss of 0.488 eV.In addition,the universality of IDTT-ED-2 F as a third component was effectively demonstrated in other photoactive systems,specifically,PM6:BTPe C9 and PTB7-Th:IEICO-4 F.This work facilitates a better understanding of the structure–property relationship for utilizing efficient EDOT-bridged NFAs in high-performance OSC applications.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21733005 and 21975115)the Shenzhen Fundamental Research Program(Nos.JCYJ20190809163011543,JCYJ20200109140801751 and JCYJ20210324120010028)+2 种基金the Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002)the Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06G587)the Shenzhen Sci-Tech Fund(No.KYTDPT 20181011104007).We also thank the SUSTech Core Research Facilities for AFM and TEM measurements.
文摘Selection of the strategically substituted alkyl chains has a significant effect to modulate the physical properties of conjugated polymers,electro-optical characteristics,and active layer morphology of the corresponding polymer solar cells(PSCs).Herein,we systematically synthesized three dibenzo[a,c]phenazine based D-π-A donor polymers named PBP-C0,PBP-C8,and PBP-C6 with different alkyl substitutions on thiopheneπ-bridges,without alkyl,2-ethylhexyl and n-hexyl groups,respectively.The absence of the alkyl chain(PBP-C0)on theπ-bridge caused poor solubility and unfavorable miscibility with the Y5 acceptor,leading to the lower photovoltaic performance.The bulky alkyl chain of 2-ethylhexyl on theπ-bridge group caused the twisting of PBP-C8 conjugated backbone,which limits the charge transport and also compromises the photovoltaic performance.In contrast,the PBP-C6-with flexible linear alkyl chains has almost planar curvature geometry resulting in the small uniform domain size and appropriate phase separation in the blend film morphology.These favorable properties enhanced the exciton generation to dissociation,charge carrier mobility,and also lowered the charge recombination.Among three polymers,PBP-C6-based devices exhibit the best PCE of 11.60%.From these results,thiopheneπ-bridge alkyl substitution demonstrated an important strategy to adjust energy level,absorption,and phase separation morphology to enhance the photovoltaic performance of the PSCs.
文摘Dye-sensitized solar cells(DSSCs)have gained critical importance as a leading emerging photovoltaic technology for low-cost power generation due to their simple production,light weight,applicability to the development of flexible photovoltaic devices,and use of abundant and inexpensive materials,including advantageous metal-free organic dyes.In this context,as a continuation of our work on DSSCs,a theoretical examination using density functional theory(DFT)and time-dependent density functional theory(TD-DFT)was conducted to evaluate the photovoltaic performance of eight new organic dyes.Each dye contains an electron donor group((E)-2-(2-(thiophen-3-yl)vinyl)-1,1′-bipyrrole),an electron acceptor group(cyanoacrylic acid(CCA)),and four auxiliary donor/acceptor groups,i.e.,3,4-ethylenedioxythiophene(EDOT),furan/benzothiadiazole(BTZ),diketopyrrolopyrrole(DPP)linked toπ-conjugated bridges such as styrene or thiophene.We calculated several parameters for each dye,including EHOMO,ELUMO,Egap,𝜆max,Eex,pen-circuit photovoltage(VOC),light harvesting efficiency(LHE),regeneration driving force(ΔGreg),electron injection driving force(ΔGinject),and excitation lifetime(𝜏)to determine the photovoltaic efficiency of each dye.The results showed that the new dyes exhibited good performance and remarkable energy-conversion efficiencies.Additionally,all investigated dyes posed as promising candidates for the generation of effective DSSC sensitizers,particularly M6,which contained a styrene-linked EDOT auxiliary donor group.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.51773142 and 51973146)the Jiangsu Provincial Natural Science Foundation(Grant No.BK20190099)+1 种基金the Collaborative Innovation Center of Suzhou Nano Science&Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Main observation and conclusion Recently,the asymmetric nonfullerene acceptors(NFAs)with acceptor-donor-acceptor(A-D-A)structure have been developed rapidly,especially for the modification of asymmetric core,asymmetric side chains and asymmetric end groups.In this work,a novel asymmetric A-D-π-A type NFA with a noncovalently fused-ring core named PIST-4F is synthesized,containing an indacenodithieno[3,2-b]dithiophene(IDT),two strong electron-withdrawing end groups and an alkylthio-substituted thiopheneπ-bridge.Benefiting from the S···S noncovalent interaction between the sulfur atom onπ-bridge and the adjacent thiophene in IDT,the PIST-4F presents nearly planar geometry and extended conjugated area,resulting in the optimized electronic properties,charge transport,and film morphology compared to the symmetric NFA PI-4F.As a result,PM6:PIST-4F-based devices achieve a higher power conversion efficiency(PCE)of 13.8%,while the PM6:PI-4F-based devices only show a PCE of 7.1%.Notably,the PM6:PIST-4F-based devices processed with nonhalogen solvent toluene exhibit an excellent PCE as high as 13.1%.These results indicate that PIST-4F is an effective acceptor for high-efficiency organic solar cells.
基金supported by the National Natural Science Foundation of China (21674007, 51825301, 21975012, 21875204, 21875204, 21734001)the financial support from the National Research Foundation (NRF) of Korea (NRF-2019R1A2C2085290, 2019R1A6A1A11044070).
文摘Benzo[1,2-b:4,5-b′]dithiophene(BDT) has been widely used to construct donor-acceptor(D-A) copolymers in organic solar cells(OSCs). However, benzo[1,2-b:4,5-b′]difuran(BDF), an analogue of BDT, has received less attention than BDT. The photovoltaic performance of BDF copolymers has lagged behind that of BDT copolymers. Here, we designed and synthesized two BDF copolymers, PBF1-C and PBF1-C-2Cl. PBF1-C-2Cl, which is composed of BDF and benzo[1,2-c:4,5-c′]dithiophene-4,8-dione connected by a chlorinated thiophene π-bridge, displays a low-lying highest occupied molecular orbital energy level,which helps in yielding a high open-circuit voltage(Voc) in OSCs. As a result, when blended with Y6, PBF1-C-2Cl-based devices showed a high Voc of 0.83 V and a power conversion efficiency(PCE) of 13.10%. To the best of our knowledge, the PCE of 13.10% is among the highest efficiency values for OSCs based on BDF copolymers.
