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Molecule‐Induced p‐Doping in Perovskite Nanocrystals Enables Efficient Color‐Saturated Red Light‐Emitting Diodes
Author(s) -
Wang Haoran,
Dou Yongjiang,
Shen Piaoyang,
Kong Lingmei,
Yuan Hao,
Luo Yun,
Zhang Xiaoyu,
Yang Xuyong
Publication year - 2020
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.202001062
Subject(s) - light emitting diode , materials science , perovskite (structure) , optoelectronics , photoluminescence , quantum efficiency , luminescence , doping , diode , passivation , nanocrystal , halide , nanotechnology , chemistry , inorganic chemistry , layer (electronics) , crystallography
Color‐saturated red light‐emitting diodes (LEDs) with emission wavelengths at around 620–640 nm are an essential part of high‐definition displays. Metal halide perovskites with very narrow emission linewidth are promising emitters, and rapid progress has been made in perovskite‐based LEDs (PeLEDs); however, the efficiency of the current color—pure red PeLEDs—still far lags behind those of other‐colored ones. Here, a simple but efficient strategy is reported to gradually down‐shift the Fermi level of perovskite nanocrystals (NCs) by controlling the interaction between NCs and their surface molecular electron acceptor—benzyl iodide with aromatic rings—and realize p‐doping in the color‐saturated 625 nm emitting NCs, which significantly reduces the hole injection barrier in devices. Besides, both the luminescence efficiency and electric conductivity of perovskite NCs are enhanced as additional advantages as the result of surface defects passivation. As a result, the external quantum efficiency for the resulting LED is increased from 4.5% to 12.9% after benzyl iodide treatment, making this device the best‐performing color‐saturated red PeLED so far. It is further found that the hole injection plays a more critical role than the photoluminescence efficiency of perovskite emitter in determining the LED performance, which implies design principles for efficient thin‐film planar LEDs.