首先制备了给体(Al Pc Cl)和受体(C70)比例为1∶1的电池器件并采用不同的温度对电池进行退火处理,发现在120℃的温度下退火电池器件的性能最好,器件的转换效率从2.28%提高到2.47%,增加了8.3%。为进一步优化电池器件的性能,制备了在相同...首先制备了给体(Al Pc Cl)和受体(C70)比例为1∶1的电池器件并采用不同的温度对电池进行退火处理,发现在120℃的温度下退火电池器件的性能最好,器件的转换效率从2.28%提高到2.47%,增加了8.3%。为进一步优化电池器件的性能,制备了在相同的活性层厚度下不同的给受体比例的电池器件,发现在给受体的厚度之比为1∶5时器件性能最好,电池开路电压为0.8 V,短路电流为10.21 m A/cm^2,填充因子为46.04%,转换效率为3.71%。展开更多
An efficient organic photovoltaic （OPV） cell with an indium-tin-oxide/CuPc/C60/Ag structure has been investigated by changing the film thickness of organic layers. A high olin-circuit voltage （Yoc） of 0.5 V, a sho...An efficient organic photovoltaic （OPV） cell with an indium-tin-oxide/CuPc/C60/Ag structure has been investigated by changing the film thickness of organic layers. A high olin-circuit voltage （Yoc） of 0.5 V, a short-circuit current density （Jsc） of 5.81 mA/cm^2, and a high power conversion efficiency （ηp） of 1.2% were achieved at an optimum film thickness. The results demonstrate that material thickness is an important factor to cell optimization, especially for maximizing the absorption rate as will as reducing the cell resistance. Experimental results also indicate that the power conversion efficiency increases from 1.2% to 1.54% as a BCP exciton blocking layer of 10 nm is introduced.展开更多
Cyano substitution has been established as a viable approach to optimize the performance of all-small-molecule organic solar cells.However,the effect of cyano substitution on the dynamics of photo-charge generation re...Cyano substitution has been established as a viable approach to optimize the performance of all-small-molecule organic solar cells.However,the effect of cyano substitution on the dynamics of photo-charge generation remains largely unexplored.Here,we report an ultrafast spectroscopic study showing that electron transfer is markedly promoted by enhanced intermolecular charge-transfer interaction in all-small-molecule blends with cyanided donors.The delocalized excitations,arising from intermolecular interaction in the moiety of cyano-substituted donor,undergo ultrafast electron transfer with a lifetime of∼3 ps in the blend.In contrast,some locally excited states,surviving in the film of donor without cyano substitution,are not actively involved in the charge separation.These findings well explain the performance improvement of devices with cyanided donors,suggesting that manipulating intermolecular interaction is an efficient strategy for device optimization.展开更多
Non-metallic particles and metallic impurities present in the feedstock affect the electrical and mechanical properties of high quality silicon which is used in critical applications such as photovoltaic solar cells a...Non-metallic particles and metallic impurities present in the feedstock affect the electrical and mechanical properties of high quality silicon which is used in critical applications such as photovoltaic solar cells and electronic devices. SiC particles strongly deteriorate the mechanical properties of photovoltaic cells and cause shunting problem. Therefore, these particles should be removed from silicon before solar cells are fabricated from this material. Separation of non-metallic particles from liquid metals by imposing an electromagnetic field was identified as an enhanced technology to produce ultra pure metals. Application of this method for removal of SiC particles from metallurgical grade silicon （MG-Si） was presented. Numerical methods based on a combination of classical models for inclusion removal and computational fluid dynamics （CFD） were developed to calculate the particle concentration and separation efficiency from the melt. In order to check efficiency of the method, several experiments were done using an induction furnace. The experimental results show that this method can be effectively applied to purifying silicon melts from the non-metallic inclusions. The results are in a good agreement with the predictions made by the model.展开更多
A new acceptor-donor-acceptor(A-D-A) type small-molecule acceptor NCBDT-4 Cl using chlorinated end groups is reported.This new-designed molecule demonstrates wide and efficient absorption ability in the range of 600–...A new acceptor-donor-acceptor(A-D-A) type small-molecule acceptor NCBDT-4 Cl using chlorinated end groups is reported.This new-designed molecule demonstrates wide and efficient absorption ability in the range of 600–900 nm with a narrow optical bandgap of 1.40 eV. The device based on PBDB-T-SF:NCBDT-4 Cl shows a power conversion efficiency(PCE) of 13.1%without any post-treatment, which represents the best result for all as-cast organic solar cells(OSCs) to date. After device optimizations, the PCE was further enhanced to over 14% with a high short-circuit current density(Jsc) of 22.35 m A cm-2 and a fill-factor(FF) of 74.3%. The improved performance was attributed to the more efficient photo-electron conversion process in the optimal device. To our knowledge, this outstanding efficiency of 14.1% with an energy loss as low as 0.55 eV is among the best results for all single-junction OSCs.展开更多
Fullerene-based electron-transporting layers(ETLs)significantly influence the defect passivation and device performance of inverted perovskite solar cells(PSCs).However,theπ-cage structures of fullerenes lead to a st...Fullerene-based electron-transporting layers(ETLs)significantly influence the defect passivation and device performance of inverted perovskite solar cells(PSCs).However,theπ-cage structures of fullerenes lead to a strong tendency to self-aggregate,which affects the long-term stability of the corresponding PSCs.Experimental results revealed that[6,6]-phenyl-C61-butyric acid methyl ester(PCBM)-based ETLs exhibit a certain degree of self-aggregation that affects the stability of the device,particularly under continuous irradiation stress.To modulate the aggregation behavior,we replaced a methyl hydrogen of PCBM with a phenyl group to yield[6,6]-phenyl-C61-butyric acid benzyl ester(PCBB).As verified through X-ray crystallography,this minor structural modification results in more non-covalent intermolecular interactions,which effectively enhanced the electron-transporting ability of the PCBB-based ETL and led to an efficiency approaching 20%.Notably,the enhanced intermolecular forces of PCBB suppressed its self-aggregation,and the corresponding device showed significantly improved stability,retaining approximately 90%of its initial efficiency after 600 h under one-sun irradiation with maximum power point tracking.These findings provide a viable approach for the design of new fullerene derivatives to tune their intermolecular interactions to suppress self-aggregation within the ETL for highperformance PSCs.展开更多
Three acceptor-donor-acceptor （A-D-A） small molecules DCAODTBDT, DRDTBDT and DTBDTBDT using dithieno[2,3-d：2＇,3＇-d＇]benzo[1,2-b：4,5-b＇]dithiophene as the central building block, octyl cyanoacetate, 3-octylrhod...Three acceptor-donor-acceptor （A-D-A） small molecules DCAODTBDT, DRDTBDT and DTBDTBDT using dithieno[2,3-d：2＇,3＇-d＇]benzo[1,2-b：4,5-b＇]dithiophene as the central building block, octyl cyanoacetate, 3-octylrhodanine and thiobarbituric acid as the end groups were designed and synthesized as donor materials in solution-processed photovoltaic cells （OPVs）. The impacts of these different electron withdrawing end groups on the photophysical properties, energy levels, charge carrier mobility, morphologies of blend films, and their photovoltaic properties have been systematically investigated. OPVs device based on DRDTBDT gave the best power conversion efficiency （PCE） of 8.34%, which was significantly higher than that based on DCAODTBDT （4.83%） or DTBDTBDT （3.39%）. These results indicate that rather dedicated and balanced consideration of absorption, energy levels, morphology, mobility, etc. for the design of small-molecule-based OPVs （SM-OPVs） and systematic investigations are highly needed to achieve high performance for SM-OPVs.展开更多
A novel A-D-A （acceptor-donor-acceptor） type non-fullerene small molecule, A201, consisting of an asymmetric thieno[1,2-b]indaceno[5,6-b＇lthienothiophene （TITI＇） unit as middle D part and 2-（3-oxo-2, 3-dihydroi...A novel A-D-A （acceptor-donor-acceptor） type non-fullerene small molecule, A201, consisting of an asymmetric thieno[1,2-b]indaceno[5,6-b＇lthienothiophene （TITI＇） unit as middle D part and 2-（3-oxo-2, 3-dihydroinden-l-ylidene） malononitrile （IC） groups as end-capped A parts was designed and synthesized. The asymmetric TITT building block showed a higher dipole moment of 0.85 Debye （1 Debye = 3.33564 × 10^-3μcm） compared with the symmetric analogues of indacenodithiophene （IDT） and indacenodithieno[3,2-b]thiophene （IDTr） of 0.098 and 0.13 Debye, respectively. The solution-processed bulk heterojunction solar cells using a benzotriazole （BTA）-based polymer of J71 as donor and A201 as acceptor, showed a power conversion efficiency （PCE） of 9.36% with an open-circuit voltage （Voc） of 0.88 V, a short-circuit current Use） of 13.15 mA cm^-2, and a fill factor （FF） of 0.B7, under the illumination of AM 1.5G at 100 mW cm^-2. The high PCE of this material combination could be attributed to its broad absorption spectrum and the high hole mobility （#h） and electron mobility （μh） of 9.56 × 10^-4 and 5.1× 10^-4 cm^2 V^-1 s^-1, respectively. These results indicate that the asymmetric electron-donating segments are promising to construct A-D-A type small molecular acceptors, which could largely enhance the diversity of building blocks to design photovoltaic materials.展开更多
文摘首先制备了给体(Al Pc Cl)和受体(C70)比例为1∶1的电池器件并采用不同的温度对电池进行退火处理,发现在120℃的温度下退火电池器件的性能最好,器件的转换效率从2.28%提高到2.47%,增加了8.3%。为进一步优化电池器件的性能,制备了在相同的活性层厚度下不同的给受体比例的电池器件,发现在给受体的厚度之比为1∶5时器件性能最好,电池开路电压为0.8 V,短路电流为10.21 m A/cm^2,填充因子为46.04%,转换效率为3.71%。
基金National Natural Science Foundation of China (No. 60425101)Young Talent Project of UESTC (060206)Program for New Century Excellent Talents in Uni-versity (No.NCET-06-0812)
文摘An efficient organic photovoltaic （OPV） cell with an indium-tin-oxide/CuPc/C60/Ag structure has been investigated by changing the film thickness of organic layers. A high olin-circuit voltage （Yoc） of 0.5 V, a short-circuit current density （Jsc） of 5.81 mA/cm^2, and a high power conversion efficiency （ηp） of 1.2% were achieved at an optimum film thickness. The results demonstrate that material thickness is an important factor to cell optimization, especially for maximizing the absorption rate as will as reducing the cell resistance. Experimental results also indicate that the power conversion efficiency increases from 1.2% to 1.54% as a BCP exciton blocking layer of 10 nm is introduced.
基金supported by the National Key R&D Program of China(No.2018YFA0209100 and No.2017YFA0303703)the National Natural Science Foundation of China(No.21922302,No.21873047,No.91850105,and No.91833305)+1 种基金the Fundamental Research Funds for the Central Universities(No.020414380126)Chun-feng Zhang acknowledges financial support from the Tang Scholar Program。
文摘Cyano substitution has been established as a viable approach to optimize the performance of all-small-molecule organic solar cells.However,the effect of cyano substitution on the dynamics of photo-charge generation remains largely unexplored.Here,we report an ultrafast spectroscopic study showing that electron transfer is markedly promoted by enhanced intermolecular charge-transfer interaction in all-small-molecule blends with cyanided donors.The delocalized excitations,arising from intermolecular interaction in the moiety of cyano-substituted donor,undergo ultrafast electron transfer with a lifetime of∼3 ps in the blend.In contrast,some locally excited states,surviving in the film of donor without cyano substitution,are not actively involved in the charge separation.These findings well explain the performance improvement of devices with cyanided donors,suggesting that manipulating intermolecular interaction is an efficient strategy for device optimization.
文摘Non-metallic particles and metallic impurities present in the feedstock affect the electrical and mechanical properties of high quality silicon which is used in critical applications such as photovoltaic solar cells and electronic devices. SiC particles strongly deteriorate the mechanical properties of photovoltaic cells and cause shunting problem. Therefore, these particles should be removed from silicon before solar cells are fabricated from this material. Separation of non-metallic particles from liquid metals by imposing an electromagnetic field was identified as an enhanced technology to produce ultra pure metals. Application of this method for removal of SiC particles from metallurgical grade silicon （MG-Si） was presented. Numerical methods based on a combination of classical models for inclusion removal and computational fluid dynamics （CFD） were developed to calculate the particle concentration and separation efficiency from the melt. In order to check efficiency of the method, several experiments were done using an induction furnace. The experimental results show that this method can be effectively applied to purifying silicon melts from the non-metallic inclusions. The results are in a good agreement with the predictions made by the model.
基金supported by the National Natural Science Foundation of China (91633301, 51773095)MoST of China (2014CB643502)+1 种基金Tianjin city (17JCJQJC44500, 17CZDJC31100)111 Project (B12015)
文摘A new acceptor-donor-acceptor(A-D-A) type small-molecule acceptor NCBDT-4 Cl using chlorinated end groups is reported.This new-designed molecule demonstrates wide and efficient absorption ability in the range of 600–900 nm with a narrow optical bandgap of 1.40 eV. The device based on PBDB-T-SF:NCBDT-4 Cl shows a power conversion efficiency(PCE) of 13.1%without any post-treatment, which represents the best result for all as-cast organic solar cells(OSCs) to date. After device optimizations, the PCE was further enhanced to over 14% with a high short-circuit current density(Jsc) of 22.35 m A cm-2 and a fill-factor(FF) of 74.3%. The improved performance was attributed to the more efficient photo-electron conversion process in the optimal device. To our knowledge, this outstanding efficiency of 14.1% with an energy loss as low as 0.55 eV is among the best results for all single-junction OSCs.
基金financial supports from the National Natural Science Foundation of China(51902110,51802102 and 21805101)the Scientific Research Funds of Huaqiao University(19BS105,16BS201 and 17BS409)+1 种基金Fundamental Research Funds for the Central Universities(ZQN-806,ZQN-PY607)the US National Science Foundation for generous support of this work under CHE1801317。
文摘Fullerene-based electron-transporting layers(ETLs)significantly influence the defect passivation and device performance of inverted perovskite solar cells(PSCs).However,theπ-cage structures of fullerenes lead to a strong tendency to self-aggregate,which affects the long-term stability of the corresponding PSCs.Experimental results revealed that[6,6]-phenyl-C61-butyric acid methyl ester(PCBM)-based ETLs exhibit a certain degree of self-aggregation that affects the stability of the device,particularly under continuous irradiation stress.To modulate the aggregation behavior,we replaced a methyl hydrogen of PCBM with a phenyl group to yield[6,6]-phenyl-C61-butyric acid benzyl ester(PCBB).As verified through X-ray crystallography,this minor structural modification results in more non-covalent intermolecular interactions,which effectively enhanced the electron-transporting ability of the PCBB-based ETL and led to an efficiency approaching 20%.Notably,the enhanced intermolecular forces of PCBB suppressed its self-aggregation,and the corresponding device showed significantly improved stability,retaining approximately 90%of its initial efficiency after 600 h under one-sun irradiation with maximum power point tracking.These findings provide a viable approach for the design of new fullerene derivatives to tune their intermolecular interactions to suppress self-aggregation within the ETL for highperformance PSCs.
基金supported by the Ministry of Science and Technology(2014CB643502,2016YFA0200200)the Natural Science Foundation of China(21404060,51422304,91433101)
文摘Three acceptor-donor-acceptor （A-D-A） small molecules DCAODTBDT, DRDTBDT and DTBDTBDT using dithieno[2,3-d：2＇,3＇-d＇]benzo[1,2-b：4,5-b＇]dithiophene as the central building block, octyl cyanoacetate, 3-octylrhodanine and thiobarbituric acid as the end groups were designed and synthesized as donor materials in solution-processed photovoltaic cells （OPVs）. The impacts of these different electron withdrawing end groups on the photophysical properties, energy levels, charge carrier mobility, morphologies of blend films, and their photovoltaic properties have been systematically investigated. OPVs device based on DRDTBDT gave the best power conversion efficiency （PCE） of 8.34%, which was significantly higher than that based on DCAODTBDT （4.83%） or DTBDTBDT （3.39%）. These results indicate that rather dedicated and balanced consideration of absorption, energy levels, morphology, mobility, etc. for the design of small-molecule-based OPVs （SM-OPVs） and systematic investigations are highly needed to achieve high performance for SM-OPVs.
基金support from the Key Research Program of Frontier Sciences,Chinese Academy of Sciences (QYZDB-SSWSLH033)the National Key Research and Development Program of China (2017YFA0206600)+1 种基金the National Natural Science Foundation of China (51673048,51473040,21504019,51773046,and 21602040)the National Natural Science Foundation of Beijing (2162045)
文摘A novel A-D-A （acceptor-donor-acceptor） type non-fullerene small molecule, A201, consisting of an asymmetric thieno[1,2-b]indaceno[5,6-b＇lthienothiophene （TITI＇） unit as middle D part and 2-（3-oxo-2, 3-dihydroinden-l-ylidene） malononitrile （IC） groups as end-capped A parts was designed and synthesized. The asymmetric TITT building block showed a higher dipole moment of 0.85 Debye （1 Debye = 3.33564 × 10^-3μcm） compared with the symmetric analogues of indacenodithiophene （IDT） and indacenodithieno[3,2-b]thiophene （IDTr） of 0.098 and 0.13 Debye, respectively. The solution-processed bulk heterojunction solar cells using a benzotriazole （BTA）-based polymer of J71 as donor and A201 as acceptor, showed a power conversion efficiency （PCE） of 9.36% with an open-circuit voltage （Voc） of 0.88 V, a short-circuit current Use） of 13.15 mA cm^-2, and a fill factor （FF） of 0.B7, under the illumination of AM 1.5G at 100 mW cm^-2. The high PCE of this material combination could be attributed to its broad absorption spectrum and the high hole mobility （#h） and electron mobility （μh） of 9.56 × 10^-4 and 5.1× 10^-4 cm^2 V^-1 s^-1, respectively. These results indicate that the asymmetric electron-donating segments are promising to construct A-D-A type small molecular acceptors, which could largely enhance the diversity of building blocks to design photovoltaic materials.
