Taiyuan University of Technology and Lund University have made important research progress in the field of two-dimensional perovskite laser

Recently, Professor Cui Yxia and Associate Professor Li Guohui from the College of Optoelectronic Engineering, Taiyuan University of Technology, and Professor Kaibo Zheng and Academician Tonu Pullerits from Lund University have made important research progress in the field of two-dimensional perovskite laser. Research to "Localized bound multiexcitons in engineered quasi-2D Perovskites grains at room temperature for efficient lasers is published in the top international journal Advanced Materials (Impact factor 32.086). The first signer of this paper is Taiyuan University of Technology. Guohui Li is the first author of this paper, and Yanxia Cui, Kaibo Zheng and Tonu Pullerits are the co-corresponding authors.

Figure 1. Screenshot of paper page

Perovskite is a promising laser gain semiconductor material due to its high optical gain, balanced carrier mobility and solution-processable properties. At present, many types of laser with high coherence and tunability have been successfully developed based on perovskite materials, such as thin films, nanocrystals and polaritons. However, the bimolecular recombination luminescence process of free electrons and holes, which dominates in three-dimensional (3D) perovskite, is less efficient at low carrier concentrations, and is highly modulated by trap-assisted non-radiative recombination, which greatly increases the concentration of carriers required for population inversion, thus limiting the energy efficiency of perovskite lasers.

Figure 2. Formation mechanism and material properties of bound multipoles in quasi-two-dimensional perovskite PEA2(CH3NH3)n-1PbnBr3n+1

Figure 3. Multiexciton spectroscopy in quasi-two-dimensional perovskite PEA2(CH3NH3)n-1PbnBr3n+1 films

Figure 4. Multiexciton stimulated radiation spectra and input-output characteristics of quasi-two-dimensional perovskite PEA2(CH3NH3)n-1PbnBr3n+1 films

Reducing the excitation threshold and minimizing Joule heat is very important for the realization of perovskite laser diodes. Although bound excitons are promising for low threshold lasers, it remains unclear how to generate bound excitons at room temperature for laser applications in devices based on quasi-two-dimensional perovskite. In view of this, the research team proposed to carry out the precise design of quasi-two-dimensional perovskite grains at room temperature so as to locally bind multiple excitons for high efficiency laser. In the experiment, the precise design of quasi-two-dimensional perovskite PEA2(CH3NH3)n-1PbnBr3n+1 microstructure was prepared by reversesolvent method. Room-temperature multiexciton radiation recombination was successfully demonstrated at an extremely low pumping energy density of 0.97μJ cm-2, which is only a quarter of what is required for 2D CdSe nanosheets, a classical two-dimensional material. In addition, well-defined translational momentum in quasi-two-dimensional perovskite grains can limit auger recombination which is not conducive to radiative recombination. In addition, quasi-two-dimensional perovskite grains are beneficial to increase the binding energy of excitons and excitons and the associated radiative recombination. Therefore, the threshold of stimulated emission at room temperature is as low as 13.7μJ cm-2, which is 58.6% lower than that of the amorphous counterpart with larger grain size. The findings of this work are expected to facilitate the development of solution-processable perovskite multi-exciton laser diodes.

Source: NetEase