Stable and efficient CdS/Sb2Se3 solar cells prepared by scalable close space sublimation

Sb2Se3 is a promising candidate for low toxicity, low-cost and high efficiency solar cells. Thin film solar cells employing Sb2Se3 as the absorber have achieved power conversion efficiencies of up to 6.5%. However, these solar cells are typically fabricated using rapid thermal evaporation, a fast deposition technique but suffer from entangled substrate and source temperatures. Here, we report on the fabrication of stable and efficient CdS/Sb2Se3 thin film solar cells using close-space sublimation process, which allows separate control of the source and substrate temperatures. This enables better control of Sb2Se3 film deposition and reduction of interfacial diffusion, leading to higher quality absorber films and improved device heterojunctions. Additionally, we introduced a novel low-cost material 4,4', 4 '', 4 '''-(9-octylcarbazole-1,3,6,8-tetrayl) tetrakis(N, N-bis(4-methoxyphenyl) aniline) (CZ-TA) as the hole transport layer (HTL) to create n-i-p structured devices. This CZ-TA HTL reduced the back contact resistance and promoted photogenerated carrier collection, boosting device photo conversion efficiency to 6.84%.