Near infrared luminescence and detector components have numerous applications in night vision, medical treatment, communications, etc. Formamidine lead halide perovskite is considered to be one of the most promising near infrared LED devices, but their performance is still affected by non-radiative recombination due to defects and inefficient carrier transport due to step barriers in devices. Therefore, it is very important to deeply understand the carrier transport mechanism in the device and reduce the band level to improve the performance of the device.
Recently, professors Fang Guoguo and Ke Weijun from the School of Physical Science and Technology of Wuhan University and Professor Wang Jianpu from Nanjing University of Technology, Jointly published Synergistic passivation and stepped-dimensional perovskite analogs enable in Nature Communications high efficiency near-infrared light-emitting diodes (High Efficiency Near-infrared Light-emitting Diodes Realized by Synergizing passivation and gradient dimension perovskite materials).
The research team introduced a series of cadmium salts into FAPbI3 precursor solution, especially the additives represented by cadmium acetate, which can play a synergistic role in passivating material defects and optimizing device band structure. In addition, cadmium salt also generates a new zero-dimensional crystal structure of perovskite-like materials (FA2CdI4). The crystal structure data information was collected and published by Cambridge Crystal Data Center.
The new zero-dimensional Fa2cDi4-type perovskites, the one-dimensional yellow phase -FAPbI3, the two-dimensional FA2FAn-1PbnI3n+1 and the three-dimensional black phase -FAPbI3 perovskites can be obtained in a one-pot synthesis. The gradient band structure can transfer charge carriers as efficiently as an energy funnel. It plays a very critical and active role in energy transfer. Therefore, the near-infrared LED device based on FAPbI3 has obtained a world record of 24.1% external quantum efficiency among similar devices, and greatly improves the working stability of the device. In addition, the device has good detection performance. Based on this, the near infrared communication of luminescent and self-driven detection twin devices is realized.