Recently, Shi Tongfei's research group, associate researcher of the Materials Application Technology Laboratory, Institute of Solid Physics, Hefei Academy of Material Sciences, Chinese Academy of Sciences, and Professor Xiao Zhengguo's research group of the University of Science and Technology of China, cooperated in Perovskite Light-Emitting Diodes, Progress in the research of PeLEDs): The researchers added a suitable amount of surfactant to the CsPbI3 perovskite precursor solution to inhibit grain growth, obtained a flat and pore-free α-CsPbI3 nanocrystalline film, and prepared the external quantum The efficiency is as high as 14.8%, and the operating life and stability have been greatly improved. Related achievements were published in ACS Applied Materials & Interfaces under the title of Efficient All-Inorganic Perovskite Light-Emitting Diodes with Improved Operation Stability.
The all-inorganic CsPbI3 perovskite has higher thermal stability than the organic-inorganic hybrid MAPbI3 perovskite, with a band gap of about 1.7 eV, which is more suitable for the preparation of visible red light emitting devices than the latter 1.5 eV. However, CsPbI3 is a delta phase with an orthogonal structure at room temperature. It is an indirect bandgap semiconductor. It is an alpha phase with a cubic structure only at a high temperature of 330oC, which limits its application in photovoltaic devices.
To this end, the researchers adjusted the size of the CsPbI3 perovskite grains by adding an appropriate amount of p-fluorobenzyl ammonium iodide (4-F-PMAI) to the CsPbI3 perovskite precursor solution, and successfully obtained the grain size Polycrystalline film less than 100 nm. Due to the high specific surface area of ​​the nanocrystals, the cubic nanostructure polycrystalline thin films with high symmetry at room temperature are more stable. In this study, by adjusting the grain size, a stable α-CsPbI3 nanocrystalline film was obtained at room temperature. At the same time, due to the quantum confinement effect of nanocrystals and the passivation of 4-F-PMAI ligand on the surface, the radiation recombination rate of α-CsPbI3 perovskite is also increased, and the film exhibits strong photoluminescence and high quantum yield. rate. The final prepared CsPbI3 light-emitting diode emits bright visible red light at 692 nm, the spectral half-height width is only 36 nm, and the external quantum efficiency is 14.8%, which is the highest efficiency value of an undoped device; The half-life of the device exceeds 1200 min, much higher than that of the organic-inorganic hybrid MAPbI3 light-emitting diode (139 min) under the same conditions; and the efficiency does not decrease during long-term storage, showing more excellent component stability. In addition, the research also shows that a small amount of Br doping can further improve the device efficiency to 18.6%, without obvious phase separation.
The work was supported by the National Joint Fund for Large Scientific Installations and the National Natural Science Foundation.
Figure 1. CsPbI3 light-emitting diode (a) schematic diagram of the device structure; (b) energy level diagram; (c) chromaticity coordinates and luminescence photos; (d) current-voltage-luminance curve; (e) external quantum efficiency-current curve ; (F) Electroluminescence spectrum.
MRL / Overhead Traction Elevator Packages
MRL / Overhead traction elevator packages are designed to provide independent and OEM elevator contractors with reliable, turn-key, custom solutions for any modernization or new construction project
Passenger Lifts
Panoramic Elevators
MRL Elevators
Villa Lifts
Home Lifts
Hospital Bed Elevators
Freight Elevators
Car Elevators
Dumberwaiter Elevators
Service Elevators
Our elevator regeneration team has extensive knowledge and is supported by our in-house technical design, manufacturing facilities, allowing us to offer modernization solutions of all types and complexity from single elevator, low rise installations to multi elevator, high rise group systems
MRL Elevator Packages,Overhead Traction Elevator Packages,Traction Elevator Packages
CEP Elevator Products ( China ) Co., Ltd. , https://www.zjelevatortravelingcable.com