Space-confined growth of large-mismatch CsPb(BrxCI1−x)3/GaN heterostructures with tunable band alignments and optical properties

Abstract

Heteroepitaxy of high-quality GaN-based heterostructures with tunable band alignment and optical properties is of central importance for their applications in electronics and optoelectronics. Incommensurate material growth on the GaN substrate with an abrupt interface is still a challenge due to the formation of high-density interface defects and structural disordering induced by the lattice mismatch. Herein, we report the heteroepitaxial growth of high-quality uniform CsPb(Br_xCl_1−x)₃ perovskite alloy nanoplatelets on the c-GaN substrate with fully tunable compositions (0 ≤ x ≤ 1) via space-confined chemical vapor deposition. The formation of large-mismatch CsPb(Br_xCl_1−x)₃/GaN heterostructures arises from relatively weak interfacial interactions (0.58–0.61 J m⁻²) that reduce the impact of the lattice mismatch on the growth. The CsPb(Br_xCl_1−x)₃/GaN heterostructures exhibit type-II band alignment with a tunable valence band offset from 0.85 to 1.34 eV and a conduction band offset from 0.45 to 0.61 eV, respectively. These heterostructures show remarkable photoluminescence quenching and reduced exciton lifetimes as compared with the CsPb(Br_xCl_1−x)₃ nanoplatelets grown on mica, which are attributed to the enhanced carrier separation and extraction efficiencies. These findings of this work provide an efficient strategy for the advancement of the versatile synthesis of large-mismatch perovskite/GaN heterostructures and exhibit their excellent potential for various functional optoelectronics.