Fabrication of antimony selenide thin film and solar cells using rapid thermal evaporation

The continuous decline of non-renewable energy sources had compelled scientists to search for alternative energy sources. Since the commercialisation of solar panels, the cost of using solar energy has significantly reduced, and as a consequence, the demand for “solar” has increase rapidly. Given the success of silicon-based solar cells and other thin film solar technologies (CdTe, CIS) alternative new materials for solar panels been investigated. Inspired by CdTe and CZTS/Se solar cells, the possibility of antimony selenide (Sb2Se3) solar cells have emerged. Many researchers have attempted to improve the efficiency of Sb2Se3 solar cell through improving device architecture and using different deposition methods for Sb2Se3 active layer. In this master’s project Sb2Se3 solar cells will be fabricated using Rapid Thermal Processing (RTP). The end goal of this Masters project is to fabricate Sb2Se3 layer with an ideal morphology, which consists of large, bulk grains to minimise surface area of grain boundaries The relationship between deposition conditions, morphology, and crystallographic orientation control have been thoroughly investigated. All adjustable parameters of the RTE furnace system, namely, deposition and equilibrium temperature, deposition time, chamber pressure, source weight, source powder treatment and the choice of apparatus have all been studied. Some of these parameters showed a stronger influence on the morphology of Sb2Se3 layers. The optimal deposition conditions were found to occur when thin films were fabricated using 250mg of Sb2Se3 powder source on AlN plate, with the equilibrium step of 350°C for 15 minutes, ramp rate of 30s, followed by the deposition of 530°C for 34s and cooled under vacuum until 150°C. Using the above optimal conditions calibrated, exploration of post-treatments on Sb2Se3 layer was performed to improve the Sb2Se3 devices’ performance. Photovoltaic performance of devices after post-sulfurisation treatment as well as using different n-type and p-type transport layers was investigated. By employing these post-treatments improvement in Jsc values were observed. However, Voc of the devices shows little or no improvement across different device architectures or post-treatments. Fabricating the Sb2Se3 thin film devices using the developed optimized conditions a champion device with the structure of ITO/CdS/Sb2Se3/P3HT/Au with a Jsc of 21.6 mAcm-2, Voc of 0.34V, FF of 38.94%, and efficiency of 2.84% was fabricated. In addition, the adaptation of other structural alteration significantly improved the photovoltaic performances of low-performing devices.