Void of lead and non-carcinogenic germanium based RbGeI3 PSC using organic charge transport layers: towards a clean and green future

The carcinogenic Pb in perovskite solar cells (PSC) has been a reason for a major pushback by environmentalists for its commercial usage. Ge has been studied widely as an alternative. Inorganic charge transport layers are not budget-friendly owing to their complicated deposition procedure. PSCs with inorganic charge transport layers report lower power conversion efficiency (PCE) than the organic charge transport layers. Although a report of RbGeI 3 -based PSC with inorganic charge transport layers(CTLs) is found in previous literature (Pindolia in JAMA 236:802–821, 2022), no study which highlights the effect of organic CTLs on RbGeI 3 -based PSC has been undertaken till date. The present study reports a simulation study of the non-carcinogenic RbGeI 3 -based PSC using organic charge transport layers through SCAPS. The defect density of the interfaces and the layers, thickness and doping density of the layers and the shunt and series resistance of solar cell (SC) is optimized. The traditional back contact material (BM), gold, increases the fabrication cost of PSC. A cost-effective alternative, carbon, as a BM is reported and the stability of the SC with temperature is established. The optimized PSC showed excellent quantum efficiency (QE) in the visible region, PCE of 21.89% and fill factor (FF) of 79.67%. This study demonstrates the potential of RbGeI 3 as a perovskite material to achieve toxicity free, clean and green renewable energy. RbGeI 3 -based PSC with organic CTLs reported in present study shows better efficiency as compared to the inorganic CTLs.