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

5 years ago

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

Tae-Woo Lee, Joo Sung Kim, Soyeong Ahn, Jung-Min Heo, Hobeom Kim, Hyung Joong Yun, Christoph Wolf, Jong Seong Bae, Himchan Cho

This paper reports highly bright and efficient CsPbBr3 perovskite light-emitting diodes (PeLEDs) fabricated by simple one-step spin-coating of uniform CsPbBr3 polycrystalline layers on a self-organized buffer hole injection layer and stoichiometry-controlled CsPbBr3 precursor solutions with an optimized concentration. The PeLEDs have maximum current efficiency of 5.39 cd A−1 and maximum luminance of 13752 cd m−2. This paper also investigates the origin of current hysteresis, which can be ascribed to migration of Br− 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− 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. Efficient and bright CsPbBr3 perovskite light-emitting diodes are achieved using a one-step fabrication of uniform CsPbBr3 polycrystalline layers on a self-organized buffer hole injection layer without synthesis of quantum dots. A study of the temperature dependence of current hysteresis and electroluminescence spectrum provides understanding of ion migration, nonradiative pathways, and electron–phonon interaction in the CsPbBr3 perovskite light-emitting diodes.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adma.201700579