Performance optimization study of lead-free CsSnGeI3 based perovskite solar cell heterostructure with different inorganic electron transport layers: A numerical simulation approach

Perovskite solar cells (PSCs) are considered to be one of the most prominent candidates for its commercialization. The meteoric properties of the PSC have always astounded the researchers. Thus, in this perspective the germanium-based PSCs are able to increase a sense of curiosity among photovoltaic (PV) researchers due to its superior stability and efficiency. In the present work, different combinations of the lead-free and non-toxic inorganic caesium tin-germanium (CsSnGeI3) based PSC structures have been studied using various electron transport layers (ETLs) (SnS2, TiO2, WS2, MoTe2 and ZnSe) and Mg–CuCrO2 as a hole transport layer due to its meteoric properties. For each ETL, the impact of materials parameters including the thickness of the various layers, absorber acceptor density, donor density, absorber defect density, absorber radiative recombination and interfacial defect density are examined to study the cell performance (such as Voc, Jsc, FF, and PCE). Moreover, the role of operating temperature, shunt resistance and series resistance in analysing the cell performance has also been checked towards its practical applicability. The results show ZnSe as the best ETL in comparison to other inorganic ETLs for CsSnGeI3 based absorber with Mg–CuCrO2 as an HTL, used in this work resulting in a good cell performance with a power conversion efficiency (PCE) of 33.24%, Voc ∼ 1.36 V, Jsc ∼ 28.02 mA/cm2 and fill factor (FF) ∼ 86.74%. The proposed simulation work may pave the way for further design and optimization of Sn-based PSCs towards practical applications.