Deposition and characterization of bismute sulphite based thin films by spin coating method

In this study, the preparation of Bi2S3 thin films by sol-gel method was investigated using environmentally friendly, naturally abundant and cheap bismuth. Bi2S3 semiconductors have naturally n-type properties and have optical band gap and absorption properties that are well suited for opto-electronic applications. Bi2S3 thin films are recently well studied and promising structures used as an alternative to toxic lead element in perovskite solar cell structures. n-Bi2S3 thin films were prepared by spin coating method and the effects of annealing environment, film thickness and annealing temperature on semiconductor properties were investigated in detail. When the annealing process of the five-layer Bi2S3 thin film is performed in a sealed metal tube, it has been observed that the sulfur vapor pressure in the environment significantly increases the film crystallinity. It has been observed that the Bi2S3 thin film prepared by annealing in the tube has crystal and orthorhombic structure from X-ray diffraction patterns. In thickness-dependent characterizations, it was determined that as the film thickness increased, the crystal size of Bi2S3 increased and the ideal film thickness was 650 nm (10 times). In UV-Vis measurements, it has been observed that the films have direct band gap properties. During the thermal characterization, by changing the annealing temperature in the range of 300-550 C, it was found that the ideal annealing temperature was 350 C and the optical band gap range of the prepared films was 1,5 eV–2,60 eV, depending on the production parameters. The electrical conductivity (σ) values of the films are between 9,79E-7 – 2,40E-5 Ω-1 cm-1. The optimum growth parameters for ideal Bi2S3 semiconductor thin films were determined as 10-layer annealing at 350 C in a tube. Keywords: Bi2S3 Thin Film, Spin coating, Perovskite, Preparation parameters.