Performance enhancement of perovskite solar cells with a modified TiO2 electron transport layer using Zn-based additives

Abstract

Perovskite solar cells (PVSCs) have recently emerged as a very attractive option in film photovoltaics. Both solvent-engineering techniques and electron transport layer (ETL) properties are necessary for high-performance PVSCs. Herein, we report a one-step spin-coating approach for the preparation of uniform and dense perovskite layers, using a mixed solvent of dimethylacetamide (DMAC) and N-methyl-2-pyrrolidone (NMP) followed by exposure to toluene to induce crystallization. We also developed a simple and quantitative method to improve the traditional compact TiO₂ ETL properties and device performance based on Zn precursor doping. The effect of Zn-doped TiO₂ was investigated using atomic force microscopy, ultraviolet-visible spectra, photoluminescence, and open-circuit photovoltage decays. The results indicate that Zn-doped TiO₂ provides a better interface between the ETL and perovskite layer than non-doped TiO₂. Light Zn doping (2 vol%) was found to be the most effective additive, and the average power conversion efficiency improved from 13.61% to 15.25%.