High Performance Metal Halide Perovskite Light‐Emitting Diode: From Material Design to Device Optimization

Abstract

Owing to superior outstanding optical properties of perovskite nanomaterials in multiple dimensions, various perovskite nanocrystals (NCs) including quantum dots, nanoplates, nanorods, and polycrystalline film, with different characteristics have been integrated into perovskite LEDs. [18][19][20][21] Among them, most studies conducted are related to perovskite LEDs based on quantum dots and polycrystalline films. [16,17,22] A considerable number of studies have focused on increasing the modest efficiency of perovskite LEDs in the early stage. [22][23][24] Strategies concerning the optimization of both the emitting layer and the device structure were employed, which led to the realization of the highest external quantum efficiency (EQE) of 11.7% for perovskite LEDs. [7] However, the poor photostability, thermal stability, and ambient stability of perovskites have limited their practical application. [25] Surface passivation, composite structure, and composite design have been developed to improve the stability of perovskite NCs. [7,[26][27][28] However, most of the strategies are inadequate for electroluminance applications. The toxicity of Pb is considerably less than that of Cd in inorganic quantum dots (QDs), [29] but, such toxicity has obstructed the further applications of metal halide perovskites. The majority of studies are currently focused on the design of lead-free perovskites. Doped perovskites have also emerged as potential materials for perovskite LEDs. Despite the large difference in efficiency and long-term stability between perovskite LEDs and organic LEDs (OLEDs), perovskite LEDs show distinct advantage with respect to cost, synthesis, and color gamut. Compared with the decade of research spent to expand the practical application of OLEDs, the development of perovskite LEDs is relatively young; despite this, acceptable achievements have been accomplished in less than three years.Thus, we aimed to develop perovskite LEDs with high efficiencies as well as high long-term stability, nontoxicity, and reproducibility. A number of studies have been conducted on perovskite LEDs, [30][31][32][33] and a marked increase in EQE in perovskite LEDs has been observed in recent years, as shown in Figure 1. New strategies for improving both perovskite materials and device structures have been applied or considered. In addition, the long-term stability and lifetime of perovskite LEDs are rarely investigated. In this context, considering the Metal halide perovskites have drawn significant interest in the past decade. Superior optoelectronic properties, such as a narrow bandwidth, precise and facile tunable luminance over the entire visible spectrum, and high photoluminescence quantum yield of up to ≈100%, render metal halide perovskites suitable for next-generation high-definition displays and healthy lighting systems. The external quantum efficiency of perovskite light-emitting diodes (LEDs) increases from 0.1 to 11.7% in three years; however, the energy conversion efficiency and the long-term stability of perovsk...

Oxalic Acid Enabled Emission Enhancement and Continuous Extraction of Chloride from Cesium Lead Chloride/Bromide Perovskite Nanocrystals

“…Benefitting from easily tunable bandgaps, excellent charge‐transport properties, high defect tolerance, and impressive photoluminescence quantum yields (PL QYs) with a narrow emission full width at half maximum (FWHM), cesium lead halide (CsPbX 3 , X = Cl, Br, and/or I) based perovskite light‐emitting diodes (PeLEDs) have reached external quantum efficiencies (EQEs) of over 20% for emission peaks in the green and the red . Green and red PeLEDs based on cesium lead halide nanocrystals (NCs) with EQEs of up to 16% and 21% have been demonstrated as well, while the blue‐emitting PeLEDs still lag behind in terms of their performance, which impedes further developments of all‐perovskite based red–green–blue displays . Even though near‐unity PL QYs have been demonstrated for CsPbCl 3 NCs with a PL centered at 410 nm, this emission wavelength does not meet the requirements for displays.…”

Operational stability of perovskite light emitting diodes

“…Organometal halide perovskites have been regarded as a promising candidate for the next-generation semiconducting materials for optoelectronics, and considerable progress has been made in the development of light emitting diodes (LEDs) in recent years [1,2]. Perovskites are a type of semiconducting material with a chemical formula of ABX 3 , where A is an organic cation, B is a divalent metal cation (Pb 2+ and Sn 2+ ), and X is halide (Cl − , Br − and I − ).…”

Recent advances and prospects toward blue perovskite materials and light‐emitting diodes

“…Over the past few years, LEDs based on metal halide perovskites (MHPs) have shown great potential as candidate in blue-emissive LEDs. 12,[21][22][23][24][25][26][27][28][29] MHPs possess excellent optoelectronic properties, [30][31][32][33][34][35][36][37][38][39] such as narrow emission linewidths (full width at half-maximum [FWHM] < 20 nm), precise tunable bandgaps (ranging from ultraviolet to near-infrared), and high charge carrier mobility and defect tolerance. The ultrahigh color purity and wide color gamut (~150%; the color gamut level for the national television standards committee [NTSC] standard is <100%) grant MHP LEDs great prospects in display applications.…”