Strategy to improve the efficiency of tin selenide based solar cell: A path from 1.02 to 27.72%

Solar energy is one of the most reliable, clean, and cheap renewable energy sources. One significant obstacle to harnessing this energy is cheap and efficient material to convert solar energy into electrical. Many materials are being searched like CIGS, CZTS, etc. Recently, there has been a focus on Sb2Se3 and SnSe types of material because they are made of few elements, have higher absorption coefficients, and are made from earth-abundant materials. Taking one experimental report as a base and using the SCAPS-1D simulation software, we have tried to explore the factors affecting the performance of tin selenide-based solar cells. The device structure was glass/Mo/SnSe/CdS/i-ZnO/ITO. An SnSe film with thickness 1.3 μm showed the efficiency of 1.02%. By adjusting the parameters the efficiency of the device was optimized. SnSe solar cell is sensitive to the shallow acceptor density, conduction and valence band density of states, and the radiative recombination coefficient (RRC). For a defect-free SnSe absorber (with RRC ≤ 1E−6 cm−3, VB-DOS 1.8E16 and CB-DOS 2.2E15) and back contact with WF = 5.2 eV (i.e. Ni) 27.72% efficiency can be achieved. Also, the thickness of the CdS layer is optimized to 20 nm concerning environmental issues. Results of this simulation can pave the strategy to improve the SnSe as an efficient solar cell absorber material.