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 (ABX₃) 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.

Keywords: light-emitting diodes; nanoparticle; organic–inorganic hybrid perovskite; polycrystalline film; vivid display.

Fig. 1.

Major trend of display technology. Data are taken from references as follows: OLEDs, refs. –; QD LEDs, refs. –; and PeLEDs, refs. –.

Fig. 2.

(A) Schematic of crystal structure, (B) schematic of emission of metal halide perovskites, and (C) FWHM and dimension of perovskite, inorganic QD, and organic emitters.

Fig. 3.

(A) External quantum efficiency versus luminance characteristics of visible PeLEDs. Data are taken from refs. – and –. (B) Schematic of PeLED structure and operation and (C) energy level diagram of materials used for HTL, ETL, and perovskite.

Fig. 4.

(A) External quantum efficiency characteristics of QD LEDs and PeNP-LEDs. Data are taken from references as follows: QD LEDs, refs. –; PeNP-LEDs, refs. –. (B) Schematic of MAPbBr₃ PeNP/PVK:PBD layer as reported in ref. (inspired by a similar drawing in ref. 81). (C) Schematic of cross-linking process. Reproduced from ref. with permission from Wiley-VCH. (D) PL transients measured at different excitation power density. Reproduced from ref. with permission from American Chemical Society.