Polarization reversal and strain effects on the band alignment and electronic properties in CuInP2S6/MoSSe heterojunctions

Abstract This study provides an in-depth analysis on the electronic properties of CuInP2S6 /MoSSe (CIPS/MoSSe) heterojunctions under the conditions of spontaneous polarization reversal and mechanical strain based on first-principles calculations. The results indicated that the polarization of the heterojunctions range from 45.82 μC/cm² for CIPS↑/MoSSe↑ to 46.53 μC/cm² for CIPS↓/MoSSe↓, with the bandgap varying from 1.23 eV to 0.19 eV. Furthermore, the CIPS↑/MoSSe↓ heterojunctions maintain a type II band alignment in the range of -6%~6% in plane strain and ±0.3 Å layer spacing variations. In addition, the power conversion efficiency of heterojunctions increased from 4.5% to 19.3% under external strain. The polarity configurations, mechanical strain and layer spacing affect the cation displacement and charge redistribution, providing building blocks for the design of novel heterojunctions with tailored polarization and electronic properties.