The development of efficient and low-cost light-to-electrocity and electricity-to-light conversion technologies is one of the most effective ways to harvest clean energy and efficient utilize. This is an important guarantee to meet China's dual carbon goals. Metal-halide perovskites possess the advantages of both inorganic and organic materials in optics, electricity, mechanical flexibility, low-temperature solution processability and so on. Therefore, the optoelectronic devices constructed with perovskite have the characteristics of high performance and low cost, and have broad market application prospects. This project focused on exploring the photophysical properties of perovskite with ultrafast spectroscopies, aiming to improve device performance and pioneer new optoelectronic applications. Firstly, the photocarrier generation, transportation and recommbination processes in perovskite were systematically investigated. A clear carrier dynamic model for perovskite has been established. The bottlenecks restricting the luminescence efficiency of perovskite were clearly elucidated. Solutions to address these bottlenecks are also proposed. Secondly, to address the stability issue which hindering the commercialization of perovskite solar cells, a novel deposition method of phase-pure quasi-two-dimensional perovskite films was developed. The perovskite solar cells constructed with this technique possess more balanced high-efficiency and good-stability, which could promote the industrialization of perovskite solar cells. In addition, a totally new ultra-short laser pulse doubling application of perovskite has been developed. High-efficiency green and blue perovskite light emitting diodes were also constructed. These works are of great scientific significance for improving the performance of perovskite light-emitting devices and expanding its optoelectronic application.

Fig 1 Dimensionality-dependent carrier recombination in metal-halide perovskites

Fig 2 Schematic diagram of non-pure phase and pure-phase quasi-two-dimensional perovskites and their optical properties comparison

Fig 3 Schematic diagram of quasi-two-dimensional perovskite multi-quantum well structure to achieve ultra-short laser pulse doubling emission