Simulation of Heat Generation in Reduced Graphene Oxide (RGO)-Contacted Lead-Free Cs₃Sb₂I₉ Perovskite Solar Cells Using COMSOL

This study investigates heat generation and thermal distribution in Cs₃Sb₂I₉ perovskite solar cells using COMSOL Multiphysics. A model integrating optical, electrical, and thermal modules was developed to analyze five key heat generation factors. The results reveal the interplay between these factors and their impact on cell performance. Reduced graphene oxide (RGO)-contacted cells exhibit favorable electrical properties, achieving a balance between voltage, current density, and efficiency, making them promising for solar energy applications. Significant heat sources include non-radiative recombination, particularly Shockley–Read–Hall (SRH) recombination in the perovskite layer. Critical junctions, such as the perovskite/TiO₂ interface, the bulk perovskite layer, and the RGO/Spiro interface, show peaks in total heat flux caused by SRH recombination and Joule heating. The RGO/Spiro junction experiences the highest Joule heat (3.4 × 10⁹ W/m³) at open-circuit voltage (V_oc), attributed to high resistive losses. Thermalization heat from excess photon energy conversion peaks at 6.0 × 10⁹ W/m³ across the perovskite layer at V, indicating significant energy loss. A 10 nm RGO layer improves thermal management by dissipating heat effectively and preventing overheating, in contrast to a 10 nm Au back contact, which retains heat over a larger area. Under short-circuit conditions (V = 0 V), Joule heat peaks at the Spiro-MeOTAD/perovskite junction (3.6 × 10⁹ W/m³), with SRH heat increasing in the perovskite layer near the TiO₂ junction (4.8 × 10⁹ W/m³). The results highlight RGO’s dual role in improving electrical conductivity and thermal dissipation, ensuring better thermal stability and enhanced performance. These findings emphasize the importance of managing thermal and electrical properties in perovskite solar cells to optimize their efficiency and longevity.