Towards efficiency enhancement of earth abundant Cu2BaSn(S,Se)4 chalcogenide solar cell using In2S3 as efficient electron transport layer

Cu₂BaSn(S,Se)₄ (CBTSSe) solar cells, are an intriguing kind of photovoltaic devices with theoretical efficiency close to 31 %. Their promise in the field of renewable energy is highlighted by their sustainable structure, as well as their low density of defects. Even with these benefits, the record efficiency for CBTSSe solar cells is now only 5.2 %. In order to identify limitations in performance and clear the path for obtaining improved practical efficiency, this emphasizes the vital requirement for deep analysis. In this work, we investigate a new structure based on Cd free In₂S₃/CBTSSe heterojunction in which an Indium (III) sulfide as ETL layer, and CBTSSe as absorber layer take the place of the traditional CdS/ CBTSSe structure. For the first time, an analytical model that incorporates a variety of recombination mechanisms occurred in CBTSSe solar cell, such as Auger, Shockley-Read-Hall (SRH), interface recombination, tunneling-enhanced recombination, and non-radiative recombinations is proposed. In our approach the reverse saturation mechanism is taken into account in the suggested model as a metric to identify the main recombination mechanism. Significantly, there is a good agreement between the outcomes of our model and the experiment. It is shown that CBTSSe bulk recombination, In₂S₃/CBTSSe interface recombination and resistances are dominating. Besides, the developed model serves as fitness function for MOGA approach to locate the optimal parameters design combination that led to optimal efficiency. We demonstrate the ability to obtain an efficiency of up to 10.12 % by carefully tuning both the CBTSSe bulk material parameters and the In₂S₃/CBTSSe interface features. Our findings demonstrate that the optimized design using In₂S₃/CBTSSe heterojunction outperforms the baseline, reaching a high J_SC of 20.57 mA/cm², V_OC of 0.88 V, and FF of 55.54 %, with appropriate band alignment at the In₂S₃/CBTSSe interface and optimized physical and geometrical parameters. The suggested approach paves the way for additional design optimization while also making it possible to identify the degradation factors that are responsible.