Efficient Inverted Polymer Solar Cells Through Modified Electron Extraction Layer

Reengineering the surface of the electron extraction layer (EEL) had been proven to be an effective and simple way to boost the efficiency of polymer solar cells (PSCs) with an inverted device structure. In this study, we report the enhanced efficiency of inverted PSCs by using a conjugated polyelectrolyte to reengineer the surface of sol-gel processed ZnO EEL. It is found that more than 22% enhancement in efficiency is observed from the inverted PSCs with ZnO EEL reengineered by conjugated polyelectrolyte, as compared with the inverted PSCs with ZnO EEL. The enhanced efficiency is originated from decreased series resistance, smooth surface roughness, and decreased work function of ZnO thin layer modified by conjugated polyelectrolyte. Our findings provide a simple approach to boost the efficiency of the inverted PSCs.