Dual-Source Evaporation Processed Novel NaBiS2 Absorber Material for Eco-Friendly and Stable Photovoltaics

Exploring and developing novel, low-cost, and environmentally friendly photovoltaic materials is a vital trend in the evolution of solar cell technology. The distinctive properties of alkali bismuth ternary sulfides have spurred increased research and application in optoelectronic devices. In this study, a novel method is reported for preparing NaBiS2 film by sequential thermal evaporation of Na2S and Bi2S3 layers followed by heating post-treatment for the first time, as well as the preparation of solar cells with NaBiS2 as the light-absorbing layer. Based on X-ray diffraction and Raman analysis, the prepared NaBiS2 film is confirmed to be a single-phase material, without the presence of any secondary phases. Additionally, the photoelectric characteristics of NaBiS2 are investigated and incorporated this material into solar cell devices. By optimizing the device architecture, the solar cell utilizing NaBiS2 as the light-absorbing layer achieved a photoelectric conversion efficiency of 2.91%, which is the highest efficiency reported for NaBiS2 solar cells up to now. The research has provided a valuable perspective and path for the development of novel photovoltaic materials in the solar cell field.