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Electrical Stress Influences the Efficiency of CH 3 NH 3 PbI 3 Perovskite Light Emitting Devices
Author(s) -
Zhao Lianfeng,
Gao Jia,
Lin YunHui L.,
Yeh YaoWen,
Lee Kyung Min,
Yao Nan,
Loo YuehLin,
Rand Barry P.
Publication year - 2017
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201605317
Subject(s) - materials science , light emitting diode , perovskite (structure) , optoelectronics , photoluminescence , ion , quantum efficiency , luminescence , band gap , stress (linguistics) , semiconductor , chemical engineering , linguistics , philosophy , engineering , physics , quantum mechanics
Organic–inorganic hybrid perovskite materials are emerging as semiconductors with potential application in optoelectronic devices. In particular, perovskites are very promising for light‐emitting devices (LEDs) due to their high color purity, low nonradiative recombination rates, and tunable bandgap. Here, using pure CH 3 NH 3 PbI 3 perovskite LEDs with an external quantum efficiency (EQE) of 5.9% as a platform, it is shown that electrical stress can influence device performance significantly, increasing the EQE from an initial 5.9% to as high as 7.4%. Consistent with the enhanced device performance, both the steady‐state photoluminescence (PL) intensity and the time‐resolved PL decay lifetime increase after electrical stress, indicating a reduction in nonradiative recombination in the perovskite film. By investigating the temperature‐dependent characteristics of the perovskite LEDs and the cross‐sectional elemental depth profile, it is proposed that trap reduction and resulting device‐performance enhancement is due to local ionic motion of excess ions, likely excess mobile iodide, in the perovskite film that fills vacancies and reduces interstitial defects. On the other hand, it is found that overstressed LEDs show irreversibly degraded device performance, possibly because ions initially on the perovskite lattice are displaced during extended electrical stress and create defects such as vacancies.