Inverted (p–i–n) perovskite solar cells using a low temperature processed TiOx interlayer

Abstract

In this article, we present the improvement in device performance and stability as well as reduction in hysteresis of inverted mixed-cation–mixed-halide perovskite solar cells (PSCs) using a low temperature, solution processed titanium oxide (TiO_x) interlayer between [6,6]-phenyl-C₆₁ butyric acid methyl ester (PCBM) and an Al electrode. Upon applying a TiO_x interlayer, device resistance was reduced compared to that of the control devices, which results in improved rectification of the characteristic current density–voltage (J–V) curve and improved overall performance of the device. PSCs with the TiO_x interlayer show an open-circuit voltage (V_oc) of around 1.1 V, current density (J_sc) of around 21 mA cm⁻², fill factor (FF) of around 72% and enhanced power conversion efficiency (PCE) of 16% under AM1.5 solar spectrum. Moreover, devices with the TiO_x interlayer show improved stability compared to devices without the TiO_x interlayer. This finding reveals the dual role of the TiO_x interlayer in improving device performance and stability.