Bathocuproine as a cathode interlayer for nonfullerene organic solar cells with efficiency over 17%

Abstract

Bathocuproine (BCP) is a classic cathode interlayer (CIL) in organic light-emitting diodes and fullerene-based bilayer-structured organic solar cells (OSCs). However, the BCP hasn't yet been reported in recently emerging nonfullerene-based OSCs. In this work, we report that the BCP can be a very efficient CIL for nonfullerene-based OSCs, which show a power conversion efficiency over 17%. An important note is that the BCP can't work with a binary nonfullerene active layer that yields poor performance of around 11%. It is possibly ascribed to the chemical reaction between the nonfullerene acceptor and BCP. Adding fullerene (PC₇₁BM) to form a ternary active layer can deliver high performance, where the interaction between BCP and the nonfullerene acceptor can be passivated by the addition of fullerene via charge transfer. This work shows the potential application of classic BCP in efficient nonfullerene OSCs.