Wet-chemical surface texturing of AZO substrate for improved perovskite solar cells

Aluminum-doped zinc oxide (AZO) is a promising substrate for perovskite solar cells (PSCs) because of its low cost, easy accessibility, and good conductivity. However, its relatively low transmittance with low resistance and inevitable reflectance loss makes it unfavorable for high-performance AZO-based PSCs. Herein, a simple and effective strategy that textures the surface of AZO substrate via a diluted HCl etching, is developed to boost PSC performance. The textured AZO substrate exhibits greater haze, higher transmittance, and lower reflectance for permitting more photons to reach and be absorbed within PSCs. In addition, the textured AZO substrate not only exhibits improved surface wettability that can enhance the buried interfacial contact and enable the growth of high-quality perovskite film, but also possesses reduced oxygen vacancies and lower work function (WF) that can suppress the recombination and reduce the energy barrier for electron extraction. As a result, the PSC on textured AZO substrate shows improved fill factor (FF, 70 %) and enhanced short-circuit current density (J sc , 23.7 mA/cm 2 ) compared with the reference cells (63 % and 21.1 mA/cm 2 ), yielding a much-increased power conversion efficiency (PCE) from 13.9 % to 17.6 %. The present work opens the door for the employment of AZO substrate in future commercialization of PSCs.