Electronic, photocatalytic, and optical properties of a two-dimensional BC2N@SiC2 high-low heterojunction.

Abstract

Photoexcited electrons and holes in traditional type-I heterostructures suffer from insufficient spatial separation, limiting their effectiveness in optoelectronic and photocatalytic devices. In this study, we develop a novel BC2N@SiC2 high-low heterojunction and thoroughly investigate its electronic, photocatalytic, and optical properties using the DFT + G0W0 + BSE method. The calculated binding energy, phonon dispersion, and molecular dynamics simulations have suggested its stability. The band structure of BC2N@SiC2 exhibits a type-I band alignment, characterized by a favorable bandgap. Unlike traditional type-I heterojunctions, the BC2N@SiC2 structure features a potential barrier and a distinct interfacial electric field. This configuration effectively enhances the separation of charge carriers and aligns band edges optimally with the redox potentials of water. Notably, the BC2N@SiC2 heterojunction can efficiently capture the majority of incident sunlight (visible and near-infrared light) and achieve light absorption coefficients greater than 105 cm-1. The observed bright exciton in BC2N@SiC2 exhibits a moderate binding energy and an average radiative lifetime of several nanoseconds. These findings suggest that the novel high-low junction in the BC2N@SiC2 heterojunction could play a significant role in the development of optoelectronic and photocatalytic devices.

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