Rational design of type-II nano-heterojunctions for nanoscale optoelectronics

Over the last decades, great advances have been made in the development of nanoscale optoelectronics, such as solar cells, photodetectors, and light-emitting diodes. The design of heterojunctions with highly desirable interface properties and consequently controllable carrier transfer is of vital importance to construct high-performance optoelectronic devices. The type-II nano-heterojunctions, which facilitates the spatial separation of the electrons and holes, hold particular interests in developing high-performance optoelectronics. This review presents an overview of the material and structural design strategies, such as precise tuning of chemical composition and crystal structure, interface strain engineering, structural optimization, and external field stimulates, with the emphasis on the photophysical properties of type-II heterojunctions. Additionally, synthetic strategies for efficient material and structural modulation are also summarized. Lastly, several emergent optoelectronic applications based on the type-II heterojunctions, such as photonic memory, photonic synapses, and optical communication are discussed. We hope this review can provide comprehensive guidance for the future development of designing and realizing high-performance nanoscale optoelectronic devices based on type-II heterojunctions.