Fabrication and analysis of Bi₂O₃/Si heterojunction for solar cell applications

Bismuth oxide (Bi₂O₃) nanoparticles were synthesized via a green route and integrated into Bi₂O₃/Si heterojunction solar cells. Structural analysis confirmed the monoclinic α-Bi₂O₃ phase with a nanoscale crystallite size, while SEM revealed a uniform morphology. Optical studies showed a direct band gap suitable for absorbing visible light. Photoluminescence spectra exhibited dual emissions at 498 nm and 250 nm, attributed to defect states and quantum confinement, highlighting the dual role of Bi₂O₃ as both absorber and transparent window layer. Electrical characterization under dark conditions demonstrated rectifying diode behavior, confirming the formation of a junction. Capacitance–voltage analysis yielded a built-in potential of 0.71 V and a depletion width of 3.66 µm, indicating efficient charge separation. The current-voltage results under illumination indicated an open-circuit voltage of 180 mV, a short-circuit current density of 3.5 µA/cm², a fill factor of 14.4%, and an efficiency of 0.91%. These results confirm that the interface engineering improves photovoltaic cell performance. They highlight the significant benefits of using environmentally friendly Bi₂O₃/Si heterojunctions.