An extensive study of the impact of graphene passivation on HTLs (PTAA and NiO) in MAPBI3 and Cs3Bi2I9-based inverted perovskite solar cells for thermal stability in SCAPS 1D framework

An investigation of the modification of transport layers of inverted perovskite solar cells has been extensively studied as an interface layer, using various techniques to minimize recombination and improve hole and electron extractions, which is critical as it affects the cell's performance. This research is aimed to passivate in the HTL/absorber interface by inserting graphene as a hole extraction layer to minimize the phase transition changes caused by vanadium dioxide (VO2) interface from the experimental finding at low and high temperature resulting in unstable performance. The device is modeled and simulated using a solar cell capacitance simulator (SCAPS) based on the input parameters from the literature. The research objectives are to examine the impact of graphene in eight (8) configurations using two-hole transport layer (HTL) layers of poly[bis(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA) and nickel oxide (NiO) in methylammonium lead iodide (MAPbI3) and cesium bismuth halide (Cs3Bi2I9) devices from existing literature and a single bilayer electron transport layer (ETL) of PCBM/BCP. The device is further optimized where the impact of absorber thickness on recombination was explored, absorber doping densities, interface defects, operating temperatures, and series/shunt resistances within the ranges of 0.1--1 mu m, 1011-1018 cm- 3 , 1011-1020 cm-3 , 25 degrees C- 85 degrees C, default (0)-10 Omega-cm2, and 500-5000 Omega-cm2, respectively. Devices with graphene passivation demonstrated thermal stability at 85 degrees C compared to those of 25 degrees C, with power conversion efficiency (PCE) improvements from 10.43 to 12.71 % and 10.07 to 16.30 % for PTAA and NiO in MAPbI3-based devices, respectively. For Cs3Bi2I9-based devices, PCE values increased from 10.910 to 19.426 % and 7.21 to 13.930 % for the PTAA and NiO HTLs, respectively. These findings explore the potentials of graphene as the interface layer to replace VO2 for charge carrier transport in an inverted p-i-n structures.