In this paper,we investigated the recombination dynamics of photogenerated charge carriers in a poly(3-hexylthiophene)(P3HT):[6,6]-phenyl-C 61-butyric acid methyl ester(PC 61 BM) blend system with donor-acceptor ratio...In this paper,we investigated the recombination dynamics of photogenerated charge carriers in a poly(3-hexylthiophene)(P3HT):[6,6]-phenyl-C 61-butyric acid methyl ester(PC 61 BM) blend system with donor-acceptor ratio of 1:1 before and after solvent annealing treatment.The technique of transient photocurrent and photovoltage measurements were used,and charge carriers were photogenerated by a 7 ns laser pulse at room temperature(298 K).In transient photocurrent measurement,we observed some differences in the saturation extracted charge in P3HT:PCBM solar cells with different power efficiencies.In addition,the bimolecular recombination coefficient is found to be 3.5×10-13 cm 3 s-1 for annealed devices,while 9.5×10-12 cm3 s-1 for as-cast devices.In the transient photovoltage measurement,we found that the photovoltage decay can be fitted by power-law equation at long time scale.The exponent parameter is 2.6 for annealed devices,which can be described as trap-free bimolecular recombination;is 1.76 for as-cast device due to the trap-limited bimolecular recombination.These experimental results indicate that the nanomorphology of active layer indeed have influence on charge carriers dynamics in P3HT:PCBM blend systems.展开更多
基金supported by the National Natural Science Foundation of China (20933010,21133001 and 21173266)the National Basic Research Program of China (2009CB20008)
文摘In this paper,we investigated the recombination dynamics of photogenerated charge carriers in a poly(3-hexylthiophene)(P3HT):[6,6]-phenyl-C 61-butyric acid methyl ester(PC 61 BM) blend system with donor-acceptor ratio of 1:1 before and after solvent annealing treatment.The technique of transient photocurrent and photovoltage measurements were used,and charge carriers were photogenerated by a 7 ns laser pulse at room temperature(298 K).In transient photocurrent measurement,we observed some differences in the saturation extracted charge in P3HT:PCBM solar cells with different power efficiencies.In addition,the bimolecular recombination coefficient is found to be 3.5×10-13 cm 3 s-1 for annealed devices,while 9.5×10-12 cm3 s-1 for as-cast devices.In the transient photovoltage measurement,we found that the photovoltage decay can be fitted by power-law equation at long time scale.The exponent parameter is 2.6 for annealed devices,which can be described as trap-free bimolecular recombination;is 1.76 for as-cast device due to the trap-limited bimolecular recombination.These experimental results indicate that the nanomorphology of active layer indeed have influence on charge carriers dynamics in P3HT:PCBM blend systems.
