Enhanced comprehensive performance of carbon-based hole-transport-layer-free CsPbI2Br solar cells by a low-cost and stable long chain polymer

Abstract

Hole-transport-layer (HTL)-free CsPbI₂Br solar cells based on a carbon electrode have attracted widespread interest because they have a simple device configuration and good light and thermal stability, and moreover are independent of high-cost HTLs and precious metal electrodes. However, the device performance including the power conversion efficiency (PCE) and operation stability is limited by the poor crystallinity of CsPbI₂Br, the mismatched energy levels and poor contact between the carbon electrode and the perovskite layer. Herein, a simple but effective additive strategy is reported to efficiently improve the crystallinity and reduce the surface roughness of the CsPbI₂Br layer, thus remarkably boosting the PCE and meanwhile enhancing the working stability by adding a low-cost and stable long chain polymer, i.e., acrylonitrile butadiene styrene (ABS) into CsPbI₂Br. The corresponding device delivers a boosted PCE of 14.27% from 11.80% for the control device without ABS addition.