Spin-Coating Process of an Inorganic Sb2S3 Thin Film for Photovoltaic Applications

The inorganic semiconductor Sb2S3 is a representative absorber material for inorganic-organic hybrid solar cells. Till date, Sb2S3 is normally deposited by the chemical bath deposition (CBD) method. However, the formation of antimony oxides cannot be avoided by the conventional CBD method, resulting in deep traps and causing a backward recombination of the generated charge carriers. In addition, the CBD method requires a long deposition time and thickness control of the Sb2S3 thin film by the CBD method is difficult because of the exponential growth behavior of this method. In order to overcome these drawbacks of the conventional CBD method, a simple spin coating process for depositing the Sb2S3 thin film is proposed in our work. Various process conditions of the Sb2S3 spin coating process such as the composition and concentration of the precursor solutions, the number of spin coatings, and the spin speed are varied. We have investigated the effect of the process conditions on the morphology, the chemical composition, and the crystalline structure of the spin-coated Sb2S3 thin films. By optimizing the process conditions, uniform and high quality Sb2S3 thin films are successfully obtained by the spin coating process. To estimate the feasibility of the spin-coated Sb2S3 thin films as absorber materials, planar Sb2S3 solar cells consisting of Au/Poly-3-hexylthiophene/Sb2S3/bl-TiO2/FTO are fabricated and the photovoltaic properties are investigated.This work was supported by the DGIST R&D Programs of the Ministry of Science, ICT & Future Planning of Korea (16-EN-03)