A room-temperature CuAlO2 hole interfacial layer for efficient and stable planar perovskite solar cells

Abstract

The fabrication and device parameters of inverted planar heterojunction (PHJ) organic–inorganic lead mixed-halide (CH₃NH₃PbI_3−xCl_x) perovskite based solar cells (PSCs) using a:CuAlO₂ as the hole selective buffer layer between the ITO electrode and PEDOT:PSS were demonstrated. Thin films of a:CuAlO₂ were derived from a pre-fabricated polycrystalline CuAlO₂ ceramic target by using the direct current (d.c.) magnetron sputtering technique. The one-step spin coating method was used to prepare the perovskite layer. A short circuit current density (J_sc) of 21.98 mA cm⁻², an open circuit voltage (V_oc) of 0.88 V, a fill factor (FF) of 0.75 and a power conversion efficiency (PCE) of 14.52% were achieved for the optimized device. These improved device parameters were also accompanied by improved stability as a result of sandwiching the ambient stable a:CuAlO₂ layer with decent conductivity between the ITO and the PEDOT:PSS layers. The versatility of this material application was also demonstrated as a similar improvement in device performance and stability, which was observed by using the prepared a:CuAlO₂ in another perovskite solar cell system based on CH₃NH₃PbI₃ prepared by the two-step spin-coating method.