Tailoring defects in electron transporting Zn2SnO4 layers by multilayer engineering and Cr doping towards efficient and stable carbon-based perovskite solar cells

Abstract

The quality of the electron transporting layer (ETL) is crucial for perovskite solar cell (PSC) performance and stability. Defects in the ETL can cause charge recombination losses and device instability. Herein, crystalline chromium-doped zinc stannate (Cr-doped Zn2SnO4) nanoparticles bilayered with a compact zinc tin oxide (c-ZTO) are proposed as an efficient ETL in PSCs. It was found that Cr incorporation improved the quality of the ZTO crystal by inducing more crystal lattice oxygen, reducing the surface defects, and narrowing the particle size distribution. A perovskite film with larger grains was achieved on the Cr-doped ZTO film. The best PSC showed power conversion efficiency (PCE) of 15.32% and a reduction in the device hysteresis effect. The PSC based on Cr-doped ZTO exhibited superior thermal and UV light stability compared to the conventional single c-ZTO PSC. The main improvement in device performance and device stability was attributed to the suppression of defect trap density. Additionally, the colloidal Cr-doped ZTO solution could be reused for at least 10 months, making it suitable for industrial PSC manufacturing due to the negligible solution aging effect. Our bilayered c-ZTO/Cr-ZTO nanoparticles provide a high quality ETL, offering great potential for efficient and stable PSCs.