Fully-covered slot-die-coated ZnO thin films for reproducible carbon-based perovskite solar cells

Abstract

The spin-coating process is generally used for depositing the electron transporting layer (ETL) of a perovskite solar cell (PSC). However, this technique is not compatible for potential large-scale and high-throughput manufacturing. Herein, the deposition of ZnO thin films was developed via a homemade slot-die coater setup on a 3-axis CNC platform to achieve high-quality ETLs. It was found that the deposition parameters play an important role on morphology control. By carefully optimising the process parameters, fully-covered and compact ZnO thin films were achieved. With the optimised ZnO ETL, carbon-based PSC offered the highest power conversion efficiency (PCE) of 10.81%. Moreover, PSCs with slot-die-coated ZnO films showed much better reproducibility and superior storage stability over 500 h than those with spin-coated ones. The particular reason for performance improvement was the enhancement in surface properties of ZnO ETLs, resulting in the reduction of interfacial charge recombination. This work facilitates the opportunity for high-quality and cost-effective thin film deposition on large-scale production applicable for photovoltaics as well as other optoelectronic applications.