Enhanced carrier management and photogenerated charge dynamics for selenium (Se) film photovoltaics.

This article focuses on improving the performance of selenium (Se) solar cells by optimizing the n-type buffer layer (NBL) using polyacrylic acid (PAA)-modified Alfa-tin oxide (SnO₂) colloids, termed P-Alfa-SnO₂. The incorporation of PAA with carboxylic functional groups enhances film coverage, reduces SnO₂ nanoparticle aggregation, passivates interface defects, and improves charge extraction at the NBL/Se interface, leading to decreased trap density and suppressed charge recombination. These modifications result in enhanced photovoltaic parameters, achieving a power conversion efficiency (PCE) of 5.82%, with an open-circuit voltage (V_OC) of 0.870 V, short-circuit current density (J_SC) of 10.77 mA/cm², and fill factor (FF) of 0.621. The study demonstrates that P-Alfa-SnO₂ films provide a simple and effective strategy to advance Se solar cell performance through improved carrier management and interface engineering.