Boosting quantum-structured solar cell light absorption through compressively strained superlattices

Abstract

The escalating demand for improved energy conversion efficiency in vehicular applications of solar cells underscores the need for innovative solutions. This study focuses on enhancing the current density of GaAs middle cells within conventional Ge-based triple-junction solar cells to realize unprecedented levels of energy conversion efficiency. We introduced a novel superlattice configuration termed a compressively strained superlattice (CSSL) and demonstrated its integration into a p-i-n junction GaAs solar cell, achieving a current density increase of 1.03 mA cm−2 over conventional GaAs solar cells. Prior investigations have explored a strain-balanced superlattice (SBSL) to enhance GaAs middle cell current density. However, our findings establish the superiority of the CSSL over the SBSL in terms of current density improvement, with the CSSL featuring 1.59 times more quantum wells per unit length than the SBSL. This increase in quantum well quantity significantly enhances light absorption efficiency and consequently, the current density.