Two simple molecular acceptors, NIDBT and NIDT, bearing the same end groups of 2-（3-oxo-2,3-dihydro-1H-inden-1-ylidene）malononitrile （INCN） yet with different core units, indenofluorenodithiophene （IDBT） and ind...Two simple molecular acceptors, NIDBT and NIDT, bearing the same end groups of 2-（3-oxo-2,3-dihydro-1H-inden-1-ylidene）malononitrile （INCN） yet with different core units, indenofluorenodithiophene （IDBT） and indaceno[2,1-b：6,5-b＇]dithiophene （IDT）, respectively, were adopted to fabri- cate polymer solar cells by blending with a narrow bandgap polymer donor, PBDBTBTT-Hex （P3）. The incorporation of benzene rings into the molecular skeletons generates a negative effect on the photovoltaic performance of resultant molecular acceptor, rendering an inferior power conversion efficiency of 2.45%, compared to 4.05% for the NlDT-based bulk-heterojunction solar cells. Detailed comparison on photovoltaic parameters indicates that the fusion by incorporating two separated benzene rings into the IDT core renders molecular acceptor of weakened intermolecular interaction with the pol- ymer donor, which results in over-aggregated phase separation, unbalanced charge transport, and serious recombination within the photovoltaic devices. The work contributes to a deep understanding of the effect of skeleton-fusion strategy for designing high-performance molecular acceptors.展开更多
Indacenodithiophene(IDT)derivatives are kinds of the most representative and widely used cores of small molecule acceptors(SMAs)in organic solar cells(OSCs).Here we systematically investigate the influence of end-grou...Indacenodithiophene(IDT)derivatives are kinds of the most representative and widely used cores of small molecule acceptors(SMAs)in organic solar cells(OSCs).Here we systematically investigate the influence of end-group fluo rination density and position on the photovoltaic properties of the IDT-based SMAs IDIC-nF(n=0,2,4).The absorption edge of IDIC-nF red-shifts with theπ-πstacking and crystallinity improvement,and their electronic energy levels downshift with increasing n.Due to the advantages of J_(sc)and FF as well as acceptable V_(oc),the difluorinated IDIC-2 F acceptor based OSCs achieve the highest power conversion efficiency(PCE)of 13%,better than the OSC devices based on IDIC and IDIC-4 F as acceptors.And the photovoltaic performance of the PTQ10:IDIC-2 F OSCs is insensitive to the active layer thickness:PCE still keep high values of 12.00%and 11.46%for the devices with active layer thickness of 80 and 354 nm,respectively.This work verifies that fine and delicate modulation of the SMAs molecular structure could optimize photovoltaic performance of the corresponding OSCs.Meanwhile,the thickness-insensitivity property of the OSCs has potential for large-scale and printable fabrication technology.展开更多
Two conjugated polymers(PulDTBD and PulDTQ)with un symmetric side chai ns have been prepared for polymer solar cells using two other polymers(PIDTBD and PIDTQ)with symmetric side chains as control compounds.The combi ...Two conjugated polymers(PulDTBD and PulDTQ)with un symmetric side chai ns have been prepared for polymer solar cells using two other polymers(PIDTBD and PIDTQ)with symmetric side chains as control compounds.The combi nation of methyl a nd 4-hexylphenyl side chai ns on the same bridged carb on can en sure good solubility,decrease tt-tt stacking dista nces,and bring proper miscibility with PC71BM simultaneously.Therefore,the corresp on ding polymer solar cells(PSCs)based on donor polymers with un symmetric side chains exhibited enhanced short-circuit current density(■)and power conversion efficiency(PCE)compared with those of control polymers.The PIDTBD and PIDTQ based devices possessed low PCE of 2.13%and 1.48%,while PCEs of devices based on PulDTBD and PulDTQ were improved to 3.93%and 4.12%,respectively.The results demonstrate that unsymmetric side chain engineering of conjugated polymers is an effective approach to achieve high performance PSCs.展开更多
A fused-ring electron acceptor IDT-2BR1 based on indacenodithiophene core with hexyl side-chains flanked by benzothiadiazole rhodanine was designed and synthesized.In comparison with its counterpart with hexylphenyl s...A fused-ring electron acceptor IDT-2BR1 based on indacenodithiophene core with hexyl side-chains flanked by benzothiadiazole rhodanine was designed and synthesized.In comparison with its counterpart with hexylphenyl side-chains(IDT-2BR),IDT-2BR1exhibits higher highest occupied molecular orbital(HOMO)energy but similar lowest unoccupied molecular orbital(LUMO)energy(IDT-2BR1:HOMO=-5.37eV,LUMO=-3.67eV;IDT-2BR:HOMO=-5.52eV,LUMO=-3.69eV),red-shifted absorption and narrower bandgap.IDT-2BR1 has higher electron mobility(2.2×10^(-3)cm^2 V^(-1)s^(-1))than IDT-2BR(3.4×10^(-4)cm^2 V^(-1)s^(-1))due to the reduced steric hindrance and ordered molecular packing.Fullerene-free organic solar cells based on PTB7-Th:IDT-2BRl yield power conversion efficiencies up to 8.7%,higher than that of PTB7-Th:IDT-2BR(7.7%),with a high open circuit voltage of0.95 V and good device stability.展开更多
基金The authors gratefully acknowledge the financial support from National Basic Research Program of China [973 Program, No. 2014CB643502）, the Strategic Priority Research Program of the Chinese Academy of Sciences （No. XDB12010200）, the National Natural Science Foundation of China （Nos. 91333113, 21572234, 61505225）.
文摘Two simple molecular acceptors, NIDBT and NIDT, bearing the same end groups of 2-（3-oxo-2,3-dihydro-1H-inden-1-ylidene）malononitrile （INCN） yet with different core units, indenofluorenodithiophene （IDBT） and indaceno[2,1-b：6,5-b＇]dithiophene （IDT）, respectively, were adopted to fabri- cate polymer solar cells by blending with a narrow bandgap polymer donor, PBDBTBTT-Hex （P3）. The incorporation of benzene rings into the molecular skeletons generates a negative effect on the photovoltaic performance of resultant molecular acceptor, rendering an inferior power conversion efficiency of 2.45%, compared to 4.05% for the NlDT-based bulk-heterojunction solar cells. Detailed comparison on photovoltaic parameters indicates that the fusion by incorporating two separated benzene rings into the IDT core renders molecular acceptor of weakened intermolecular interaction with the pol- ymer donor, which results in over-aggregated phase separation, unbalanced charge transport, and serious recombination within the photovoltaic devices. The work contributes to a deep understanding of the effect of skeleton-fusion strategy for designing high-performance molecular acceptors.
基金supported by the Natural Science Foundation of China(Nos.51820105003,51863002 and 51973042)Excellent young scientific and technological talents of Guizhou,China(No.QKHPTRC[2019]5652)。
文摘Indacenodithiophene(IDT)derivatives are kinds of the most representative and widely used cores of small molecule acceptors(SMAs)in organic solar cells(OSCs).Here we systematically investigate the influence of end-group fluo rination density and position on the photovoltaic properties of the IDT-based SMAs IDIC-nF(n=0,2,4).The absorption edge of IDIC-nF red-shifts with theπ-πstacking and crystallinity improvement,and their electronic energy levels downshift with increasing n.Due to the advantages of J_(sc)and FF as well as acceptable V_(oc),the difluorinated IDIC-2 F acceptor based OSCs achieve the highest power conversion efficiency(PCE)of 13%,better than the OSC devices based on IDIC and IDIC-4 F as acceptors.And the photovoltaic performance of the PTQ10:IDIC-2 F OSCs is insensitive to the active layer thickness:PCE still keep high values of 12.00%and 11.46%for the devices with active layer thickness of 80 and 354 nm,respectively.This work verifies that fine and delicate modulation of the SMAs molecular structure could optimize photovoltaic performance of the corresponding OSCs.Meanwhile,the thickness-insensitivity property of the OSCs has potential for large-scale and printable fabrication technology.
文摘Two conjugated polymers(PulDTBD and PulDTQ)with un symmetric side chai ns have been prepared for polymer solar cells using two other polymers(PIDTBD and PIDTQ)with symmetric side chains as control compounds.The combi nation of methyl a nd 4-hexylphenyl side chai ns on the same bridged carb on can en sure good solubility,decrease tt-tt stacking dista nces,and bring proper miscibility with PC71BM simultaneously.Therefore,the corresp on ding polymer solar cells(PSCs)based on donor polymers with un symmetric side chains exhibited enhanced short-circuit current density(■)and power conversion efficiency(PCE)compared with those of control polymers.The PIDTBD and PIDTQ based devices possessed low PCE of 2.13%and 1.48%,while PCEs of devices based on PulDTBD and PulDTQ were improved to 3.93%and 4.12%,respectively.The results demonstrate that unsymmetric side chain engineering of conjugated polymers is an effective approach to achieve high performance PSCs.
基金supported by the National Basic Research Program of China(2013CB834702)the National Natural Science Foundation of China(91433114)
文摘A fused-ring electron acceptor IDT-2BR1 based on indacenodithiophene core with hexyl side-chains flanked by benzothiadiazole rhodanine was designed and synthesized.In comparison with its counterpart with hexylphenyl side-chains(IDT-2BR),IDT-2BR1exhibits higher highest occupied molecular orbital(HOMO)energy but similar lowest unoccupied molecular orbital(LUMO)energy(IDT-2BR1:HOMO=-5.37eV,LUMO=-3.67eV;IDT-2BR:HOMO=-5.52eV,LUMO=-3.69eV),red-shifted absorption and narrower bandgap.IDT-2BR1 has higher electron mobility(2.2×10^(-3)cm^2 V^(-1)s^(-1))than IDT-2BR(3.4×10^(-4)cm^2 V^(-1)s^(-1))due to the reduced steric hindrance and ordered molecular packing.Fullerene-free organic solar cells based on PTB7-Th:IDT-2BRl yield power conversion efficiencies up to 8.7%,higher than that of PTB7-Th:IDT-2BR(7.7%),with a high open circuit voltage of0.95 V and good device stability.
