期刊
ACS NANO
卷 15, 期 4, 页码 6316-6325出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.1c00872
关键词
lead-free perovskites; hybrid quantum wells; semiconducting organic cations; charge injection; energy transfer; light-emitting diodes
类别
资金
- Office of Naval Research [N00014-19-1-2296]
- College of Engineering and Davidson School of Chemical Engineering of Purdue University
- U.S. Department of Energy, Office of Basic Energy Sciences [DE-SC0016356]
Researchers have developed an efficient and stable LED device using organic semiconductor barrier layers, which enable the conversion of emission energy from the organic layer into higher energy emission from the perovskite layer, leading to improved device performance and stability.
Two-dimensional perovskites that could be regarded as natural organic-inorganic hybrid quantum wells (HQWs) are promising for light-emitting diode (LED) applications. High photoluminescence quantum efficiencies (approaching 80%) and extremely narrow emission bandwidth (less than 20 nm) have been demonstrated in their single crystals; however, a reliable electrically driven LED device has not been realized owing to inefficient charge injection and extremely poor stability. Furthermore, the use of toxic lead raises concerns. Here, we report Sn(II)-based organic-perovskite HQWs employing molecularly tailored organic semi-conducting barrier layers for efficient and stable LEDs. Utilizing femtosecond transient absorption spectroscopy, we demonstrate the energy transfer from organic barrier to inorganic perovskite emitter occurs faster than the intramolecular charge transfer in the organic layer. Consequently, this process allows efficient conversion of lower-energy emission associated with the organic layer into higher-energy emission from the perovskite layer. This greatly broadened the candidate pool for the organic layer. Incorporating a bulky small bandgap organic barrier in the HQW, charge transport is enhanced and ion migration is greatly suppressed. We demonstrate a HQW-LED device with pure red emission, a maximum luminance of 3466 cd m-2, a peak external quantum efficiency up to 3.33%, and an operational stability of over 150 h, which are significantly better than previously reported lead-free perovskite LEDs.
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