Developing efficient and stable lead-free perovskite solar cells (PSCs) has become a research goal as environmental concerns arising from the toxicity of lead-based perovskite solar cells persist. However, lead-free alternatives tend to lag behind their lead-based counterparts in terms of performance. In addition, despite the perovskite grain shape and structure plays a significant role in photon absorption, little to no significant dedicated research has been conducted to explore shape-driven photovoltaic properties of PSCs.
To address these issues, researchers from China's Wenzhou University have utilized COMSOL Multiphysics software to investigate the perovskite grain shape-modulated photovoltaic optimization aiming to systematically enhance the overall performance of lead-free all-perovskite tandem solar cells (APTSCs).
The team used CsSnI3 (narrow bandgap ∼ 1.3 eV) and Cs3Sb2Br9 (with a wide bandgap ∼ 2 eV) to construct and optimize single junction/tandem lead-free PSCs. Notably, COMSOL Multiphysics, as a 3D simulation tool, enabled the scientists to investigate how the grain morphology of the absorber layer influences photovoltaic performance of lead-free PSCs.
Their findings suggest that perovskite grain with cylindrical shape exhibit excellent photovoltaic performance, as the single-junction lead-free devices with narrow and wide bandgap exhibited optimal power conversion efficiency (PCE) of 31.67 % and 21.15 %, respectively.
Furthermore, the scientists successfully constructed 2T lead-free perovskite tandem solar cells by combining the optimized single-junctions and PCE value as high as 33.28 % was achieved.
These results not only demonstrate the significant potential of lead-free perovskite materials but also validate that perovskite grain shape is a crucial parameter for light trapping in solar absorber materials which has the potential to effectively overcome the current material's limitations and can boost the device efficiency of lead-free perovskite tandem devices.
