Paper Title
OPTIMIZATION STUDY OF LEAD-FREE CsSnGeI3PEROVSKITE BASED SOLAR CELL STRUCTURES

Abstract
This work deals with the simulation and optimization of a configured solar cell: FTO/PCBM/CsSnGeI3/PTAA/Au, whose three main layers are the absorber made of the inorganic and lead-free perovskite material CsSnGeI3 with a band gap energy of 1.5 eV, surrounded by two carrier transport layers, the electron transport layer ETL of PCBM and the hole transport layer HTL of PTAA. An appropriate simulation model was detailed, with the subsequent aim of calculating the current-voltage curve and photovoltaic performance of the cell, taking into account the impact of varying certain physical parameters such as the defect density in the absorber and the defect density at the interface between the absorber and its surrounding ETL and HTL layers, which influence recombination in the absorber and at the interfaces, the architectural dimensions of the main layers, which have an impact on the amount of absorption, and the operating temperature, which varies photovoltaic performance. The results obtained showed that the optimized FTO/ZnSe/CsnGeI3/Spiro-OMeTAD/Au configured structure, whose optimized thicknesses of the main layers and optimized physical parameters are detailed in the work, achieved a power conversion efficiency of 17.7% with Voc=0.8865 V Jph= 24.43 mA/cm² and FF = 76.51%. In the study, this single cell was used as the top sub-cell in a tandem solar cell structure, once combined with a silicon bottom sub-cell and again with a CIGS sub-cell, and an efficiency of over 35 % was achieved. Simulation results for the single and tandem structures studied were compared with similar devices reported, and a good correlation was found. This work contributes to the development of efficient and non-toxic perovskite solar cell structures for single and tandem devices. Keywords - Perovskite, Photovoltaic, Solar Cell, Simulation, Tandem, Thin-Film, Lead-Free