In the last few years, organic–inorganic halide perovskites (OIHP) have gained significant attention in the optoelectronics community and become one of the most popular research topics. Due to their fascinating properties, including wide-range tunable band gap, long charge carrier diffusion length, high absorption coefficient, and easy solution processability, they have become one of the most promising classes of low-cost and easily scalable semiconductor materials for application in various optoelectronic devices such as solar cells, photodetectors, and light-emitting diodes. To achieve the best performance and viable technologies for future energy harvesting, display and light sensing prototypes, in addition to the OHIP active layer, the use of interfacial charge transporting layers is crucial. These interfacial charge-transporting layers not only enhance the performance of optoelectronic devices but also effectively protect the active environmentally unstable OHIP layer. In this review, we summarize the development and utilization of organic interfacial materials and OIHP in solar cells, photodetectors and light-emitting diodes. In each section, the working principle and the development of a wide range of hole/electron transporting materials are discussed. Finally, an outlook and further research directions as well as useful rules for the design of novel hole/electron transporting materials are proposed.
