The researchers have prepared all inorganic perovskite green LED, and the stability has been greatly improved

Recently, Professor Shi Zhifeng et al in cooperation with the Jilin University Zhengzhou University Key Laboratory of material physics of the Ministry of education, has made new progress in the new perovskite based light-emitting devices, successfully prepared a highly efficient and stable inorganic perovskite LED green, the device exhibited excellent stability. The results were published in the nano letters.

Perovskite materials initially attracted widespread attention in the field of solar cell, within a few years of perovskite based solar cell has conversion efficiency of more than 22%, showing good application prospect. However, due to the poor film forming properties and relatively low fluorescence quantum efficiency, the development in the field of luminescence, display and laser has been slow. At the same time, the stability is not high, which has restricted the application of traditional organic inorganic hybrid perovskite materials in optoelectronic devices. In order to overcome the above difficulties, the researchers tried to improve the luminescent properties of the device by using all inorganic perovskite CsPbBr3 quantum dots as the light-emitting layer. The new quantum dots were prepared by a simple method of low temperature solution, and the fluorescence quantum efficiency was more than 85%.

Figure 1: the top p-MgNiO/CsPbBr3/n-MgZnO/n+-GaN device structure diagram, and luminescence photos in 8 volt bias; below for the perovskite LED continuous work 10 hours under the light intensity attenuation curve, illustration shows the device in different working hours of light photos.

For the perovskite LED, the work stability is the key to its practical application. At present, the perovskite LED has been reported as an organic or polymer material as the charge injection layer, and its instability is not conducive to the long time operation of the device under high current. Zhengzhou University Key Laboratory of material physics of the Ministry of education innovation of Shi Zhifeng et al used inorganic oxide semiconductor as charge injection layer, first prepared inorganic heterostructure CsPbBr3 based on quantum dots (p-NiMgO/CsPbBr3/n-MgZnO/n+-GaN), brightness of the device can reach 3809cd/m2, the external quantum efficiency is about 2.39%. More importantly, the multilayer heterostructure devices in packaging, air condition, the DC drive more than 10 hours of continuous work, its stability is much better than the traditional polymer materials (such as PCBM, PEDOT etc.) as carrier injection layer perovskite LED. The device structure can give full play to the unique advantages of CsPbBr3 quantum dots with high optical gain, and combined with Zn (Mg) O, Ni (Mg) O thin films with mature technology, stable and conductive good crystallinity etc., is of great significance for the study of the physical mechanism of light induced development and electrical model of perovskite LED. This provides a new idea for the design and development of high stability perovskite LED in the future.

The work was supported by the National Natural Science Foundation of China, the China Postdoctoral Science Foundation and the outstanding young teacher development fund of Zhengzhou University.

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