Hot pressing-induced selenium solar cells and the SCAPS simulation for its indoor photovoltaics application

Selenium (Se), with a bandgap of 1.9 eV, is highly suitable for indoor photovoltaics (IPVs) due to its strong absorption in the visible spectrum, especially under common indoor light sources such as LEDs. However, selenium films exhibit poor wettability with conventional electron transport layers, making it challenging to achieve high coverage films. To address this, we propose a selenium film fabrication process based on a novel hot pressing. By introducing shear forces, we successfully obtained high-quality selenium films onto a dense TiO₂ layer without additional interface layers and constructed a prototype device with a simple FTO/TiO₂/Se/C architecture, achieving a power conversion efficiency (PCE) of 0.27 %. Furthermore, through performance simulations using SCAPS software under different light sources, we found that with a selenium layer thickness of above 1 μm, a reduced defect densities and an optimized electron transport layer, the device PCE could reach 21.37 % under indoor LED lighting, highlighting the potential of Se-based devices for energy harvesting in low-light, indoor environments.