Luminescent coupling effect in wafer-bonded III-V on silicon multijunction solar cells

Abstract

Strong luminescent coupling (LC) effect reduces current mismatch in III-V-based multijunction solar cells and consequently improves their power conversion efficiency. The LC current production in the Si bottom cell of InGaP/AlGaAs//Si triple junction solar cells having different sizes was investigated to determine the cell area dependence of LC effect. This was probed through laser beam-induced current (LBIC) mapping. The areal mapping was then assessed by obtaining the absolute difference between the quantum efficiencies calculated from the fitted LBIC map and simulated LC current considering uniform distribution using a quasi-two-dimensional electro-optical prediction model. At 9.17 suns concentration difference between the AlGaAs middle cell and the current-limiting Si bottom cell, the absolute LC quantum efficiency differences ranged between 0.16% and 1.68% in various cell sizes, which indicate potential current production increase if the LC current is made uniform.