Theoretical study of the strong piezo-phototronic effect in 2D monochalcogenides for multi-junction solar cells

Abstract

The piezophototronic effect is a new scientific area that investigates the synergistic interactions of piezoelectric, semiconductor, and photoexcitation features. This effect is seen in crystals lacking inversion symmetry, where applied strain alters electronic transport and provides a way to modify material properties. Monolayer 2D semiconductors, such as TMDCs and group IV monochalcogenides, have higher piezoelectric coefficients than conventional piezoelectric materials. This study suggests creating a stable and high-performance Multijunction Solar Cell (MJSC) using the piezo-phototronic effect. The emphasis is on single-type 5-layer 2D monochalcogenides such as SnS, SnSe, GeS, and GeSe, which employ band gap engineering. Surprisingly, the ultrathin parallel-connected solar cell achieves an electric power conversion efficiency of over 31% when tested under blackbody radiation, exceeding the recognized S-Q limit. The piezophototronic effect improves solar cell performance while also addressing voltage mismatch issues. This work introduces a novel approach to developing and manufacturing high-efficiency and robust monolithic multijunction photovoltaic solar cells (MJPSC) based on 2D monochalcogenides.