High-Efficiency Solution-Processed Inorganic Metal Halide Perovskite Light-Emitting Diodes.

Cho, Himchan; Wolf, Christoph; Kim, Joo Sung; Yun, Hyung Joong; Bae, Jong Seong; Kim, Hobeom; Heo, Jung-Min; Ahn, Soyeong et al. · Adv Mater · 2017

basic_science · Level V

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Abstract

This paper reports highly bright and efficient CsPbBr<sub>3</sub> perovskite light-emitting diodes (PeLEDs) fabricated by simple one-step spin-coating of uniform CsPbBr<sub>3</sub> polycrystalline layers on a self-organized buffer hole injection layer and stoichiometry-controlled CsPbBr<sub>3</sub> precursor solutions with an optimized concentration. The PeLEDs have maximum current efficiency of 5.39 cd A<sup>-1</sup> and maximum luminance of 13752 cd m<sup>-2</sup> . This paper also investigates the origin of current hysteresis, which can be ascribed to migration of Br<sup>-</sup> anions. Temperature dependence of the electroluminescence (EL) spectrum is measured and the origins of decreased spectrum area, spectral blue-shift, and linewidth broadening are analyzed systematically with the activation energies, and are related with Br<sup>-</sup> anion migration, thermal dissociation of excitons, thermal expansion, and electron-phonon interaction. This work provides simple ways to improve the efficiency and brightness of all-inorganic polycrystalline PeLEDs and improves understanding of temperature-dependent ion migration and EL properties in inorganic PeLEDs.