High performance organic solar cells based on ZnO: POT2T as an effective cathode interfacial layer

Abstract

Interface engineering in organic solar cells (OSCs) plays an important role in improving electron extraction and suppressing carrier recombination. In this article, the improvement of device was achieved by doping POT2T into ZnO as a new electron transport layer (ETL). For PTB7-Th: PC71BM system, the device fabricated by using ZnO as ETL achieved a PCE of 9.03% with a JSC of 17.33 mA/cm2, a VOC of 0.783V and a FF of 64.17%. After doping 5wt% POT2T in ZnO, the JSC increased to 18.01 mA/cm2 and the FF increased slightly to 69.87%, as a result, the PCE increased to 9.84% with about 10% enhancement. The enhancement is attributed to the improved electron transport and conductivity, optimized ZnO surface morphology after adding POT2T, resulting in higher JSC and FF. Therefore, doping POT2T into ZnO as an ETL is a simple and effective method for obtaining high efficient OSCs.