Cadmium sulfide (CdS) is one of the most promising electron-transporting materials (ETMs) in perovskite solar cells (PSCs). In the present study, an ultra-thin CdS layer was prepared as the ETL using N-methyl thiourea (NMT) and introduced into a planar PSC. This new CdS ETL effectively enhanced the current without sacrificing other parameters such as the open-circuit voltage and fill factor, resulting in superior photovoltaic performance.