Optimized current and voltage matching in high-efficiency bifacial III − V/silicon multijunction solar cells with enhanced spectral albedo

This study presents a comprehensive investigation into the design, optimization, and performance of a mechanically stacked III-V/TOPCon tandem solar cell, primarily focusing on achieving voltage and current matching under varying illumination conditions. The proposed tandem configuration comprises a III-V triple-junction top cell (1 cm × 1 cm), exhibiting a V_oc of 2.70 V, J_sc of 13.95 mA/cm², FF of 84.39 %, and a PCE of 31.79 % under standard 1-sun illumination. The bottom layer integrates four series-connected TOPCon cells (1.5 cm × 1.5 cm each), achieving a combined V_oc of 2.70 V, J_sc of 14.02 mA/cm², FF of 87.08 %, and an efficiency of 32.96 %. The tandem module was fabricated using a mechanical stacking approach, where an III-V triple-junction top cell was physically aligned over series-connected TOPCon bottom cells without direct material bonding. Electrical performance was optimized through voltage and current matching, and spectral response was enhanced by rear-side albedo illumination ensuring efficient charge collection and energy conversion. Under 0.4-sun rear illumination, the tandem module achieved a J_sc of 16.00 mA/cm², V_oc of 2.70 V, FF of 84.63 %, and a peak efficiency of 36.56 %, representing the best configuration in this study. These findings underscore the potential of mechanically stacked tandem modules for next-generation photovoltaic technologies, offering advantages in scalability, spectral optimization, and electrical performance for high-efficiency solar energy applications.