Improving organic solar cell efficiency using solution processed poly (3-hexylthiophene) buffer layer

Abstract

In this work, it has been shown that inserting buffered poly 3-hexylthiophene layer between hole transport layer and blended polymer: fullerene active layer of the organic solar cell (OSC) improves the power conversion efficiency by 34% over the conventional OSC. The buffer layer also increases short-circuit current density from 4.97 ± 0.2 mA/cm 2 (without buffer layer) to 6.12 ± 0.3 mA/cm 2 (with buffer layer). These improvements are mainly due to increased absorption in the buffered polymer layer. The buffer layer insertion leads to better charge carrier collection and lesser hole recombination at the hole transport interface, which increases shunt resistance and reduces the series resistance of the device. In addition, the insertion of the buffer layer also shows significant improvement in the absorbance spectrum and external quantum efficiency of the device.