High-efficiency perovskite-polymer bulk heterostructure light-emitting diodes
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.
Cite
@article{arxiv.1804.09785,
title = {High-efficiency perovskite-polymer bulk heterostructure light-emitting diodes},
author = {Baodan Zhao and Sai Bai and Vincent Kim and Robin Lamboll and Ravichandran Shivanna and Florian Auras and Johannes M. Richter and Le Yang and Linjie Dai and Mejd Alsari and Xiao-Jian She and Lusheng Liang and Jiangbin Zhang and Samuele Lilliu and Peng Gao and Henry J. Snaith and Jianpu Wang and Neil C. Greenham and Richard H. Friend and Dawei Di},
journal= {arXiv preprint arXiv:1804.09785},
year = {2019}
}