Organic ammonium salt-assisted pinhole-free CuSCN films for carbon-based perovskite solar cells

Abstract

Due to the low cost and strong hydrophobicity of carbon electrodes, carbon-based perovskite solar cells (C-PSCs) have drawn much attention. Copper(I) thiocyanate (CuSCN) is a favorable hole transport layer in perovskite solar cells (PSCs) because of its high chemical stability, high conductivity, and high hole mobility, but pinholes often appear during CuSCN film fabrication. In this work, organic ammonium salt, phenethylammonium iodide (PEAI), has been applied to modify the CuSCN film. The results indicated that PEAI not only eliminated the pinholes, but also passivated the perovskite film and enhanced the interfacial connection. Therefore, the power conversion efficiency (PCE) of C-PSCs increased by about 11%. The stability test showed that the C-PSCs, without any encapsulation, could maintain 70% of the initial efficiency after storage for 800 h in ambient air with 60%–70% relative humidity at room temperature.