TY - JOUR
T1 - Engineering Perovskite Nanocrystal Surface Termination for Light-Emitting Diodes with External Quantum Efficiency Exceeding 15%
AU - Xiao, Zhengguo
AU - Kerner, Ross A.
AU - Tran, Nhu
AU - Zhao, Lianfeng
AU - Scholes, Gregory D.
AU - Rand, Barry P.
N1 - Funding Information:
The authors acknowledge the support by the Air Force Office of Scientific Research under Award no. FA9550-18-1-0037. Z.X. acknowledges the support of the National Natural Science Foundation of China (Award # 51872274).
Publisher Copyright:
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2019/3/14
Y1 - 2019/3/14
N2 - Hybrid organic–inorganic metal halide perovskites are particularly promising for light-emitting diodes (LEDs) due to their attractive optoelectronic properties such as wavelength tunability, narrow emission linewidth, defect tolerance, and high charge carrier mobility. However, the undercoordinated Pb and halide at the perovskite nanocrystal (NC) surface causes traps and nonradiative recombination. In this work, the external quantum efficiency of iodide-based perovskite LEDs is boosted to greater than 15%, with an emission wavelength at 750 nm, by engineering the perovskite NC surface stoichiometry and chemical structure of bulky organoammonium ligands. To the stoichiometric precursor solution for the 3D bulk perovskite, 20% molar ratio of methylammonium iodide is added in addition to 20% excess bulky organoammonium iodide to ensure that the NC surface is organoammonium terminated as the crystal size is decreased to 5–10 nm. This combination ensures minimal undercoordinated Pb and halide on the surface, avoids 2D phases, and acts to provide nanosized perovskite grains which allow for smooth and pinhole-free films. As a result of time-resolved photoluminescence (PL) and PL quantum yield measurements, it is possible to demonstrate that this surface modification increases the radiative recombination rate while reducing the nonradiative rate.
AB - Hybrid organic–inorganic metal halide perovskites are particularly promising for light-emitting diodes (LEDs) due to their attractive optoelectronic properties such as wavelength tunability, narrow emission linewidth, defect tolerance, and high charge carrier mobility. However, the undercoordinated Pb and halide at the perovskite nanocrystal (NC) surface causes traps and nonradiative recombination. In this work, the external quantum efficiency of iodide-based perovskite LEDs is boosted to greater than 15%, with an emission wavelength at 750 nm, by engineering the perovskite NC surface stoichiometry and chemical structure of bulky organoammonium ligands. To the stoichiometric precursor solution for the 3D bulk perovskite, 20% molar ratio of methylammonium iodide is added in addition to 20% excess bulky organoammonium iodide to ensure that the NC surface is organoammonium terminated as the crystal size is decreased to 5–10 nm. This combination ensures minimal undercoordinated Pb and halide on the surface, avoids 2D phases, and acts to provide nanosized perovskite grains which allow for smooth and pinhole-free films. As a result of time-resolved photoluminescence (PL) and PL quantum yield measurements, it is possible to demonstrate that this surface modification increases the radiative recombination rate while reducing the nonradiative rate.
KW - light-emitting diodes
KW - nanocrystal
KW - organic–inorganic hybrid perovskite
KW - surface engineering
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U2 - 10.1002/adfm.201807284
DO - 10.1002/adfm.201807284
M3 - Article
AN - SCOPUS:85060703223
SN - 1616-301X
VL - 29
JO - Advanced Functional Materials
JF - Advanced Functional Materials
IS - 11
M1 - 1807284
ER -