CdSe/ZnS量子点敏化太阳能电池电子注入与光伏性能表征

合成了CdSe/ZnS核壳结构量子点(QDs), 将其作为光敏剂吸附在TiO2纳米晶薄膜上, 组装成量子点敏化太阳能电池(QDSSCs), 从电子注入速率和电池性能两方面对QDSSCs进行了表征. 为了定量研究ZnS层包覆对电子注入的影响, 运用飞秒瞬态光谱技术, 测试了包覆ZnS前后, CdSe-TiO₂体系的电子注入速率. 实验测得ZnS包覆前后电子注入速率分别为7.14×10¹¹s^-1和2.38×10^-11s^-1, 可以看出包覆后电子注入速率明显降低, 仅为包覆前的1/3. 电池器件J-V性能测试表明, ZnS作为绝缘层包覆在CdSe的表面有效提高了QDSSCs的填充因子和稳定性, 但同时也导致了效率的降低. 上述结果说明了电子注入速率的降低是导致电池电流和效率下降的重要原因, 为今后优化核壳结构QDSSCs的电流和效率提供了依据.

Electron Injection and Photovoltaic Properties in CdSe/ZnS Quantum Dot Sensitized Solar Cells

CdSe/ZnS core/shell quantum dots (QDs) were synthesized and adsorbed onto nanocrystalline TiO₂ films for application in quantum dot sensitized solar cells(QDSSCs). Femtosecond transient absorption spectra was measured to investigate the effect of the ZnS shell coating on electron injection from CdSe QDs to nanocrystalline TiO₂ films. The results showed a decrease in electron injection rate from 7.14×10¹¹s^-1 to 2.38×10^-11s^-1 after ZnS shell coating, which means the electron injection rate only remained 1/3. The fill factor(FF) and stability of QDSSCs were improved by ZnS coating, but the photocurrent decreased, resulting in an overall decrease in efficiency. The slower electron injection rate is found to be the main cause for this decrease in photocurrent and efficiency, which matches well with the photovoltaic property test. These results provide information for optimizing the current and efficiency of QDSSCs employing core/shell QDs.