Progress in indium (III) sulfide (In2S3) buffer layer deposition techniques for CIS, CIGS, and CdTe-based thin film solar cells

Recent progress with indium (III) sulfide (In2S3)-buffered thin film solar cells (TFSC) was briefly reviewed. In2S3 has emerged as a promising low-hazard buffer (or window) material, and has proven to improve the properties of the solar cells, while reducing toxicity. Various deposition techniques have been employed to synthesize In2S3 films on different types of substrates. Until now, atomic layer deposition (ALD) and ionic layer gas atomic reaction (ILGAR) techniques have been the two most successful, yielding maximum energy conversion efficiencies up to 16.4% and 16.1%, respectively. The impact of varied deposition parameters upon the In2S3 film properties and performance of cadmium (Cd)-free solar cells has been outlined. A comparative/operational analysis (solar cell efficiencies above 9% reported for cell area ⩽ 1 cm2) of various buffer layers used in two primary types of TFSC technology: chalcopyrite (CIS/CIGS)- and CdTe-based solar cells was also performed to measure the progress of In2S3 compared to its counterparts.