Recent advances toward high efficiency halide perovskite light emitting diodes: Review and perspective

Abstract

PCE of 22% was reported. This PCE value is comparable to those of polycrystalline silicon solar cells, making it the most promising candidate for renewable energy generation in the near future. [11] In addition to the successful use of HPs in solar cells, these materials have also exhibited excellent performance in a wide range of other applications, such as photodetec-tors, [12-15] field-effect transistors, [16-18] gas sensors, [19] resistive-switching memory devices, [20-25] and light-emitting diodes (LEDs). [26-31] Among these, halide perov-skite light-emitting diodes (HPLEDs) shown unprecedented performance with maximum luminance values of up to 91 000 cd m −2 and external quantum effi-ciencies (EQEs) of over 11.7%. [32,33] More interestingly, the emission color of HPs can be easily tuned from blue to green or red by simply changing the halide anion from Cl − to Br − , or I − , making these potential materials for use in white-color-emission LEDs in the future. [34-36] The high performance of HPLEDs is attributed to the intrinsic properties of HP materials, such as their low defect density, high crystallinity, high absorption, high PLQY, and efficient charge transport. The crucial parameters that determine the performance of LEDs are the external quantum efficiency (EQE), the power efficiency (PE), the current efficiency (CE), the turn-on voltage (V ON), the maximum luminance (L max), and the stability. The EQE, PE, and CE are calculated using Equation (1), (2) and (3), accordingly EQE IQE 0 η = ⋅ (1) where IQE is the internal quantum efficiency, and η 0 is the fraction of photons emitted to free space P IV PE / = (2) where P is the power emitted into free space L J CE / = (3) where L is the luminance of the LEDs, and J is the current density. Here, the current strategies for obtaining highly efficient HPLEDs will be discussed (Figure 1a). We begin with approaches for controlling the morphology and crystalliza-tion of 3D HP films for high-efficiency HPLEDs. Secondly, we Organic-inorganic halide perovskite materials have attracted significant attention during the last few years because of their superior properties for electronic and optoelectronic devices, such as their long charge-carrier diffusion lengths and high photoluminescence quantum yields of up to 100% with tunable bandgaps over the entire visible spectral range. In addition to solar cells, light-emitting diodes represent a fascinating application for halide perov skite materials. Here, the recent progress relating to halide perovskite LEDs is reviewed. The current strategies for improving the performance of halide LEDs, focusing on morphological engineering, dimensional engineering, compositional engineering, surface passivation, interfacial engineering, and the plasmonic effect are discussed. The challenges and perspectives for the future development of halide perovskite LEDs are also considered. Perovskite Light-Emitting Diodes