论文部分内容阅读
The interfaces between electrodes and the active layer play a crucial role in the light-to-electricity conversion of polymer solar cells.Zwitterions,which have positive and negative charges in the same molecule,are investigated as the electron-collection materials of polymer solar cells.Zwitterions can be processed by solution processing or vacuum deposition.They can effectively lower the work function of ITO and other metals.Both normal and inverted polymer solar cells with zwitterions were demonstrated.The photovoltaic performance depends on the chemical structure of zwitterions.Conjugated zwitterions lead to higher power conversion efficiency than non-conjugated zwitterions.For polymer solar cells with some low bandgap polymers,zwitterions can significantly improve the photovoltaic performance in comparison with the control devices with Ca.Power conversion efficiencies of about 9%were observed on polymer solar cells with zwitterions.