Enhancing the photovoltaic performance of perovskite solar cells by potassium ions doping

Abstract

Organometal halide perovskite solar cells (PSCs) have attracted much attention due to their high photovoltaic efficiency and low fabrication cost. The perovskite layer plays a critical role on the power conversion efficiency (PCE). The main issues in perovskite layer are the coverage and crystallinity of perovskite grain based on substrate. Here, potassium ions were doped into perovskite layer to improve the growth, structure, properties of perovskite films and the photovoltaic performance of PSCs. The potassium ions significantly affect the Jsc and efficiency but affect the Voc slightly. The Jsc increases from 14.73 to 19.98 mA cm−2, and the efficiency increases from 10.16 to 13.57% at the doping level of 0.5% (molar ratio). The incorporation of potassium ions into perovskite also affects the crystallisation and morphology of the perovskite films and thus the PCE of PSCs. The crystallinity and denseness of perovskite film are enhanced and crystallite size is enlarged after potassium ions are doped into perovskite layer. At the same time, hysteresis free and stable device is obtained with the PSC at the doping level of 0.5% of potassium ions (molar ratio).