Precise Preparation of CdS Thin Films for Efficient Sb2S3-y Se Y Thin-Film Solar Cells

In this work, CdS thin films were prepared by chemicalbath deposition(CBD) and Sb2S3-y Se (y) thin films were prepared by a hydrothermalmethod. Solar cells with the architecture of FTO/CdS/Sb2S3-y Se (y) /spiro-OMeTAD/Au were fabricated to evaluate thequality of CdS thin films as the electron transport layer. The precisepreparation strategy with the combination of adjusting the thicknessof CdS thin films prepared by CBD and changing the concentration ofthe CdCl2 methanol solution in the post-treatment processwas first proposed. When the CdS thin-film thicknesses were 100, 80,65, and 40 nm and the CdCl2 methanol solution concentrationwas 20 mg center dot mL(-1), the power conversion efficiencies(PCEs) of the corresponding solar cells were 7.32% of 100 nm, 7.62%of 80 nm, 8.00% of 65 nm, and 7.55% of 40 nm. When the CdS thin-filmthickness was 40 nm and the CdCl2 methanol solution concentrationsdecreased to 15, 13.3, 10, and 5 mg center dot mL(-1), thePCEs were 7.98% of 15 mg center dot mL(-1), 8.46% of 13.3mg center dot mL(-1), 7.71% of 10 mg center dot mL(-1), and 7.31% of 5 mg center dot mL(-1). Therefore, the 40nm thick compact and full-coverage CdS thin film without the appearanceof residual CdCl2 can be successfully obtained using theprecise preparation strategy and achieved an optimal PCE of 8.46%.The precise preparation strategy is also valuable to develop the ultrathin,compact, and full-coverage CdS thin film as the electron transportlayer for CdTe thin-film solar cells.