Zhengzhou University research team made new progress in high performance perovskite LED research

Recently, Associate Professor Shi Zhifeng and other key professors of the Department of Materials Physics of Zhengzhou University cooperated with Jilin University to make new progress in new perovskite-based light-emitting devices. They innovatively designed and prepared an all-inorganic heterostructure. Perovskite LEDs have much better luminous efficiency and stability than existing perovskite-based light-emitting devices. The relevant results were published online in the International Authoritative Academic Journal published in the Nano Express.

Recently, the potential application of perovskite materials in the field of luminescence has attracted widespread attention. There have been many reports on the use of perovskite materials in visible light LEDs. However, due to the poor film forming properties of the perovskite film and the relatively low fluorescence quantum efficiency, its development in the fields of luminescence, display and laser has been slow. At the same time, the low stability has also restricted the application of traditional organic-inorganic hybrid perovskite materials in optoelectronic devices. In order to overcome the above difficulties, the researchers tried to use the all-inorganic perovskite CsPbBr3 quantum dots as the luminescent layer to improve the luminous efficiency and stability of the device.

Figure 1: The structure of the p-MgNiO/CsPbBr3/n-MgZnO/n+-GaN device is shown above, and the luminescence of the device under 8 volts bias; below is the luminescence intensity decay curve of the perovskite LED for 10 hours of continuous operation. The illustration shows the illuminating photos of the device during different working hours.

In addition to the CsPbBr3 quantum dot system as a light-emitting layer, the ligand material (charge transport layer) of the perovskite LED has a great influence on the work efficiency and stability of the device. However, the perovskite-based LEDs have been reported to use organic or polymer materials as charge injection layers, and their inherent instability is not conducive to long-term operation of the device at high currents. Shi Zhifeng and others of Zhengzhou University innovatively used inorganic oxide semiconductors as charge injection layers to prepare all-inorganic heterostructures based on CsPbBr3 quantum dots (p-NiMgO/CsPbBr3/n-MgZnO/n+-GaN). The brightness is up to 3809 cd/m2 and the external quantum efficiency is about 2.39%. More importantly, the multi-layer heterostructure device can work continuously for more than 10 hours under DC drive without package or air environment, and its working stability is much better than that of traditional polymer materials (such as PCBM, PEDOT). Etc.) The perovskite LED as a carrier injection layer is reported. The device structure can fully utilize the unique advantages of high optical gain of CsPbBr3 quantum dot material, and can combine the advantages of mature process, stable conductivity and good crystallization characteristics of Zn(Mg)O and Ni(Mg)O film materials. The design and development of high-stability perovskite-based LEDs provides new ideas and is expected to promote its industrialization process.

The work was supported by the National Natural Science Foundation of China, the China Postdoctoral Science Foundation, and the Zhengzhou University Outstanding Young Teacher Development Fund.