Solution-Processed Zinc Oxide Thin Film as a Buffer Layer for Polymer Solar Cells with an Inverted Device Structure

Abstract

A solution-processed zinc oxide (ZnO) thin film as a buffer layer for polymer solar cells (PSCs) with an inverted device structure has been demonstrated. A power conversion efficiency (PCE) of 3.8% was observed from an inverted device structure with the ZnO buffer layer. Without the ZnO layer, PSCs only show a PCE of 1.67%, which is less than half the value observed from PSCs with the ZnO buffer layer. When operated at room temperature, no obvious degradation was observed from the PSCs with the ZnO layer after continuously illuminating the devices for 4 h. However, a significant degradation was observed from the PSCs without the ZnO buffer layer after illuminating the devices only for 1 h. Furthermore, PSCs with the ZnO buffer layer also show very good shelf stability; only 5% degradation was observed in PCEs after 47 days. All these results demonstrate that the ZnO buffer layer plays an important role in the enhancement of PSCs’ performance with an inverted device structure.