Numerical analysis of hole transport layer-free antimony selenide solar cells: Possible routes for efficiency promotion

Abstract

Amongst the numerous absorbers confronted in thin-film solar cell technology, antimony selenide (Sb2Se3) is regarded as an extremely promising contender as it is a non-toxic and earth-abundant besides its high-level absorption coefficient. To boost the power conversion efficiency (PCE) of Sb2Se3 solar cells, we report some design recommendations by utilizing device simulation. The device model is firstly validated by calibration of an experimental cell having a configuration of FTO/CdS/Sb2Se3/Spiro-OMeTAD/Au. Then, the optimization of a hole transport layer (HTL) free structure is carried out by tuning the conduction band offset between the electron transport layer (ETL) and the Sb2Se3 absorber and by inspecting the key absorber parameters to get the maximum available power conversion efficiency. In this context, the ternary compound material ZnMgO is found to match the optimum band alignment. Moreover, the impact of ETL parameters, like thickness, doping, and surface treatment by ammonia etching, has been analyzed to understand its underlying physics and to provide possible ways for device efficiency promotion. All simulations, conducted in this paper, are accomplished by SCAPS device simulation software under standard one Sun (AM1.5G, 100 mW/cm2) illumination at 300 K.