1. High-efficiency perovskite-polymer bulk heterostructure light-emitting diodes
- Author
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Zhao, Baodan, Bai, Sai, Kim, Vincent, Lamboll, Robin, Shivanna, Ravichandran, Auras, Florian, Richter, Johannes M., Yang, Le, Dai, Linjie, Alsari, Mejd, She, Xiao-Jian, Liang, Lusheng, Zhang, Jiangbin, Lilliu, Samuele, Gao, Peng, Snaith, Henry J., Wang, Jianpu, Greenham, Neil C., Friend, Richard H., and Di, Dawei
- Subjects
Physics - Applied Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science ,Physics - Optics - Abstract
Perovskite-based optoelectronic devices have gained significant attention due to their remarkable performance and low processing cost, particularly for solar cells. However, for perovskite light-emitting diodes (LEDs), non-radiative charge carrier recombination has limited electroluminescence (EL) efficiency. Here we demonstrate perovskite-polymer bulk heterostructure LEDs exhibiting record-high external quantum efficiencies (EQEs) exceeding 20%, and an EL half-life of 46 hours under continuous operation. This performance is achieved with an emissive layer comprising quasi-2D and 3D perovskites and an insulating polymer. Transient optical spectroscopy reveals that photogenerated excitations at the quasi-2D perovskite component migrate to lower-energy sites within 1 ps. The dominant component of the photoluminescence (PL) is primarily bimolecular and is characteristic of the 3D regions. From PL quantum efficiency and transient kinetics of the emissive layer with/without charge-transport contacts, we find non-radiative recombination pathways to be effectively eliminated. Light outcoupling from planar LEDs, as used in OLED displays, generally limits EQE to 20-30%, and we model our reported EL efficiency of over 20% in the forward direction to indicate the internal quantum efficiency (IQE) to be close to 100%. Together with the low drive voltages needed to achieve useful photon fluxes (2-3 V for 0.1-1 mA/cm2), these results establish that perovskite-based LEDs have significant potential for light-emission applications.
- Published
- 2018
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