Towards improved efficiency of SnS solar cells using back grooves and strained-SnO2 buffer layer: FDTD and DFT calculations

In this work, a novel SnS thin-film solar cell (TFSC) based on strained-SnO2 electron transport layer (ETL) combined with back grooves aspect is proposed. The density functional theory (DFT) is used to assess the influence of the unit cell volume engineering on the electronic and optical properties of SnO2 material. Simulated results demonstrate the potential of strained-SnO2 material as a junction partner of p-type SnS absorber, showing a favorable conduction band offset and thereby reduced recombination effects. Moreover, the role of back grooves texture in enhancing light-scattering effects is investigated using FDTD technique. It is revealed that the proposed SnS TFSC based on combined strained-SnO2/SnS heterostructure and optimized back grooves paradigm offers the possibility for bridging the gap between improved absorption capabilities and enhanced photo-induced carrier extraction characteristics. It is demonstrated that the optimized SnS TFSC exhibits superior performances compared to the conventional one in terms of photovoltaic parameters, offering a high short-circuit current of Isc = 28 mA/cm2, a superior open-circuit voltage of Voc = 0.47 V, a high fill factor of FF = 68.4% and over than 9% of PCE. Therefore, our work paves the way to use the strained-SnO2 buffer layer and back grooves to boost the poor performances of SnS-based TFSCs.