Enhanced Photovoltaic Performance of UMGSilicon via Boron/Phosphorus Co-Doping and Data-Driven Process Optimization

Abstract

The transition toward cost-effective photovoltaic technologies requires alternatives to high-purity polysilicon, where upgraded metallurgical-grade (UMG) silicon represents a promising candidate. Yet, the intrinsic limitations of UMG silicon namely elevated impurity concentrations, high defect densities, and shortened minority carrier lifetimes remain key barriers to its widespread adoption. In this study, we address these challenges by exploring boron (B) and phosphorus (P) co-doping in UMG silicon nanostructures as a route to performance enhancement. A multi-tiered methodology was established, integrating controlled doping experiments, advanced electrical characterization, and compact-device modeling informed by Shockley Read Hall recombination kinetics. To systematically capture process property performance relationships, a design of experiments (DOE) framework was implemented, wherein dopant concentrations, carrier lifetimes, and interfacial resistances were varied. The extracted photovoltaic parameters open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and conversion efficiency (η) were quantitatively benchmarked against undoped references. Simulation results indicated that optimized B/P co-doping reduces recombination-active defect states and enhances carrier transport, yielding Voc improvements exceeding 60 mV and FF gains up to 8% under typical operating conditions. Monte Carlo–based statistical analysis further confirmed the robustness of the identified optima, with η improvements of 15–20% compared to baseline UMG silicon. These findings substantiate the role of synergistic B/P co-doping as a technically viable and economically attractive strategy to elevate UMG silicon toward high-efficiency photovoltaics. The presented optimization framework provides not only a mechanistic understanding of dopant–defect interactions but also practical guidelines for scaling laboratory protocols to industrial solar cell manufacturing.