Advances on perovskite quantum dot electroluminescent devices

Perovskite materials display great potential in the optoelectronic applications and are considered as one of the most promising optoelectronic materials due to the advantages such as high color-rending index, wide color gamut, excellent charge-transport properties, adjustable band gap, high photoluminescence quantum efficiency, low manufacturing cost, and compatibility with flexible/stretchable devices. Applying perovskite QDs as phosphors in white light down-converted light- emitting diode (LED) or emitter materials in active matrix-QLEDs to obtain high efficiency and wide color gamut is significantly promising for next-generation high-definition information displays and high-quality lighting sources applications. In this paper, the evolution of device performance of perovskite QDs-based LEDs has been demonstrated. Significant enhancement of device performance has been realized through appropriate ligand choice and effective ligand exchange together with modifying device architectures. Meanwhile, numerous encouraging achievements have been achieved via inhibition of non-radiative recombination and enhancement of exciton binding energy, since the first perovskite LED was reported in 2014. Due to the quantum effect limited by space size, perovskite quantum dots have higher exciton binding energy, easily achievable high fluorescence quantum efficiency and narrow emission bandwidth. Because of the excellent photoelectric characteristics, perovskite quantum dots have a wide application potential in new display and solid state lighting. However, for the commercial applications, further efforts are required to elucidate the physical mechanisms and improve the device performance of perovskite QLEDs. Besides, the poor stability of perovskite QLEDs in ambient and harsh conditions has attracted a wide concern, and simultaneously, several strategies have been explored to circumvent this issue, including compositional engineering, surface engineering, matrix encapsulation and device encapsulation. Although significant advances have been made in this regard, the lifetime of perovskite QLEDs remains far away from the commercial requirements. Further strategies to stabilize perovskite QDs and prevent their decomposition are in demand. Encapsulation technology of such kind of devices should be further investigated. Moreover, to avoid the toxicity problem, stable lead-free metal halide analogues with high optoelectronic performance are also needed. Furthermore, colloidal perovskite QDs can maintain functionality under tensile strains, opening new possibilities for their applications in flexible/stretchable electronics to satisfy the future development trend of QLEDs. In recent years, perovskite quantum dots have become an important issue in the field of photoelectricity. The device performance of perovskite quantum dot light-emitting diode has advanced considerably. In this paper, the research progress of perovskite quantum dot electroluminescence devices is reviewed, the main factors restricting the electroluminescence performance of perovskite quantum dots are analyzed, and in view of the problems in devices: Poor charge transport caused by long-chain ligands, non-radiative quenching of excitons caused by surface defects, and imbalance of charge injection in devices, the improvement strategies are discussed separately. Due to the quantum effect limited by space size, perovskite quantum dots have higher exciton binding energy, easily achievable high fluorescence quantum efficiency and narrow emission bandwidth. Compared with perovskite orebody materials, perovskite quantum dots have greater application potential in the field of display and lighting. And we are convinced that a highly efficient and stable perovskite QDs-based LED will be fulfilled in the near future.