Metal halide perovskite light emitters

Abstract

Twenty years after layer-type metal halide perovskites were successfully developed, 3D metal halide perovskites (shortly, perovskites) were recently rediscovered and are attracting multidisciplinary interest from physicists, chemists, and material engineers. Perovskites have a crystal structure composed of five atoms per unit cell (ABX 3 ) with cation A positioned at a corner, metal cation B at the center, and halide anion X at the center of six planes and unique optoelectronic properties determined by the crystal structure. Because of very narrow spectra (full width at half-maximum ≤20 nm), which are insensitive to the crystallite/grain/particle dimension and wide wavelength range (400 nm ≤ λ ≤ 780 nm), perovskites are expected to be promising high-color purity light emitters that overcome inherent problems of conventional organic and inorganic quantum dot emitters. Within the last 2 y, perovskites have already demonstrated their great potential in light-emitting diodes by showing high electroluminescence efficiency comparable to those of organic and quantum dot light-emitting diodes. This article reviews the progress of perovskite emitters in two directions of bulk perovskite polycrystalline films and perovskite nanoparticles, describes current challenges, and suggests future research directions for researchers to encourage them to collaborate and to make a synergetic effect in this rapidly emerging multidisciplinary field.As human civilization went through the information revolution, display technology has been designated as a core technology to increase convenience in daily human life. In an information society, the desire of humans to see the materials more vividly in displays has significantly increased. In this aspect, major trend of the display technology is changing from high resolution and high efficiency to high color purity for realizing vivid natural colors (Fig. 1). Therefore, research on new emitting materials that can emit light with narrow full width at halfmaximum (FWHM) have been attempted. Inorganic quantum dot (QD) emitters with narrow spectra (FWHM ∼30 nm) have been significantly studied following organic emitters (FWHM >40 nm); however, size-sensitive color purity, difficult size uniformity control, and expensive material costs of inorganic QD emitters retard the progress for wide use in industry. Therefore, new emitters with size-insensitively high color purity (FWHM <20 nm) and low material cost should be developed. Among many candidates, metal halide perovskites (hereafter, "perovskites") have gained great attentions and shown the possibility for future high-color purity emitters.The first perovskites were layer-type thin films (A 2 MX 4 ) (A = organic cation; M = divalent metal; X = Cl, Br, I) (1-6).They were expected to be novel hybrid materials that had both advantages of organic materials (e.g., solution processability and low material costs) and inorganic materials (e.g., high charge carrier mobility) (7). Especially, perovskites with high color purity, easy wavelength tuning, and ...

Advances in Quantum‐Confined Perovskite Nanocrystals for Optoelectronics

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“…[3] The excellent performances are mainly attributed to their unique optoelectronic properties, such as high optical absorption coefficient, direct band gap, long carrier-diffusion length, and high carrier mobility. [4] Due to the enhanced stability and radiative recombination efficiency, the all-inorganic cesium lead halide (CsPbX 3 , X = Cl, Br, and I) perovskite nanocrystals (NCs) www.advelectronicmat.de cathode side and MAM anode side. The total peak brightness of the device was 4212 cd m −2 , while the maximum luminance and external quantum efficiency (EQE) for ITO and MAM electrode sides were 2640 cd m −2 and 0.35%, 1572 cd m −2 and 0.23%, respectively.…”

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“…Organic‐inorganic hybrid and all‐inorganic metal halide perovskite nanocrystals (NCs) have very recently emerged as interesting materials because of their superior properties for optoelectronic applications. For instance, their unique optical versatility, long charge carrier diffusion length, high photoluminescence quantum yields (PL QYs), tunable bandgaps over the entire visible spectral range, and facile synthesis, all make them increasingly effective in the field of light‐emitting diodes (LEDs), solar cells, and photodetectors …”