Query: Perovskite light-emitting diodes with external quantum efficiency exceeding 20 percent

Candidate papers:

abstract: Metal halide perovskite materials are an emerging class of solution processable semiconductors with considerable potential for use in optoelectronic devices1 3. For example, light emitting diodes (LEDs) based on these materials could see application in flat panel displays and solid state lighting, owing to their potential to be made at low cost via facile solution processing, and could provide tunable colours and narrow emission line widths at high photoluminescence quantum yields4 8. However, the highest reported external quantum efficiencies of green and red light emitting perovskite LEDs are around 14 per cent7,9 and 12 per cent8, respectively still well behind the performance of organic LEDs10 12 and inorganic quantum dot LEDs13. Here we describe visible light emitting perovskite LEDs that surpass the quantum efficiency milestone of 20 per cent. This achievement stems from a new strategy for managing the compositional distribution in the device an approach that simultaneously provides high luminescence and balanced charge injection. Specifically, we mixed a presynthesized CsPbBr3 perovskite with a MABr additive (where MA is CH3NH3) the differing solubilities of which yield sequential crystallization into a CsPbBr3/MABr quasi core/shell structure. The MABr shell passivates the nonradiative defects that would otherwise be present in CsPbBr3 crystals, boosting the photoluminescence quantum efficiency, while the MABr capping layer enables balanced charge injection. The resulting 20.3 per cent external quantum efficiency represents a substantial step towards the practical application of perovskite LEDs in lighting and display.A strategy for managing the compositional distribution in metal halide perovskite light emitting diodes enables them to surpass 20% external quantum efficiency a step towards their practical application in lighting and displays.
author_names: Kebin Lin

Jun Xing

Li Na Quan

F Pelayo Garcia Arquer

Xiwen Gong

Jianxun Lu

Liqiang Xie

Weijie Zhao

Di Zhang

Chuanzhong Yan

Wenqiang Li

Xinyi Liu

Yan Lu

Jeffrey Kirman

Edward H Sargent

Qihua Xiong

Zhanhua Wei
title: Perovskite light emitting diodes with external quantum efficiency exceeding 20 per cent
venue: Nature
year: 2018

abstract: Trihalide perovskite semiconductors are emerging as promising emitting materials in light emitting diodes in view of their low cost manufacture, solution processing, and high color purity [1] However, the highest external quantum efficiency reported for perovskite LEDs has so far resided near 14% The low photoluminescence quantum efficiency of the active layer, and an unbalanced charge injection rate, have until now kept perovskite LEDs performance well below that of the best organic and inorganic LEDs. Here we report visible perovskite LEDs that surpass the 20% quantum efficiency milestone. This stems from a new compositional distribution management strategy that simultaneously provides high luminescence and balanced charge injection. We mix a pre synthesized CsPbBr3 perovskite with MABr (MA CH3NH3) additive in the precursor; the different solubility of which yields sequential crystallization into a CsPbBr3@MABr quasi core shell structure. The MABr shell passivates nonradiative defects otherwise present in CsPbBr3 crystals, boosting their photoluminescence quantum efficiency; and the MABr capping layer enables balanced charge injection. We document as a result perovskite LEDs whose EQE reaches 20.3%
author_names: Zhanhua Wei
title: High Performance Perovskite Light Emitting Diodes with External Quantum Efficiency Exceeding 20% Achieved via Compositional Distribution Management
year: 2018

author_names: Zhibin Fang

Yongliang Shi

Jin Zhao

Ji Zhang

Zhengguo Xiao
title: Dual Passivation of Perovskite Defects for Light Emitting Diodes with External Quantum Efficiency Exceeding 20%
year: 2020

author_names: Zhengguo Xiao

Ross A Kerner

Nhu L Tran

Lianfeng Zhao

Gregory D Scholes

Barry P Rand
title: Engineering Perovskite Nanocrystal Surface Termination for Light Emitting Diodes with External Quantum Efficiency Exceeding 15%
year: 2019

abstract: In recent years, substantial progress has been made in developing perovskite light emitting diodes with near infrared, red and green emissions and over 20% external quantum efficiency. However, the development of perovskite light emitting diodes with blue emission remains a great challenge, which retards further development of full color displays and white light illumination based on perovskite emissive materials. Here, firstly, through composition and dimensional engineering, we prepare quasi two dimensional perovskite thin films with improved blue emission, taking advantages of reduced trap density and enhanced photoluminescence quantum yield. Secondly, we find a vertically non uniform distribution of perovskite crystals in the PEDOT:PSS/perovskite hybrid film. Through modulating the position of the recombination zone, we activate the majority of quasi two dimensional perovskite crystals, and thus demonstrate the most efficient blue perovskite light emitting diode to date with emission peak at 480 nm, record luminance of 3780 cd m 2 and record external quantum efficiency of 5.7%.Halide perovskite based light emitting diodes attracted intensive research interest recently but the efficiency of blue diodes is much lower than the green and red ones. Here Li et al. push up the efficiency of blue diodes through composition engineering and vertical morphology control.
author_names: Zhenchao Li

Ziming Chen

Yongchao Yang

Qifan Xue

Hin-Lap Yip

Yong Cao
title: Modulation of recombination zone position for quasi two dimensional blue perovskite light emitting diodes with efficiency exceeding 5%
venue: Nature Communications
year: 2019

abstract: The absence of highly efficient and stable blue phosphors is still a bottleneck for the development of high quality monochrome and white phosphorescent organic light emitting diodes (OLEDs) Here, we propose a chlorine functionalization strategy for blue phosphors, and a series of aromatic chlorine based high efficiency blue iridium(III) phosphors (Ir1 Ir4) containing various ancillary ligands was designed and prepared. These phosphors show intensive blue emissions withPL peaks of 468 476 nm and a high PhPL of 0.70 0.85 in dichloromethane. Using these blue phosphors as emitters, the fabricated OLEDs also realize similar blue emissions with the peaks located at 472, 484, 476, and 476 nm for the Ir1 Ir4 based OLEDs, respectively. Moreover, the Ir2 and Ir3 based OLEDs exhibit extremely high EQEs exceeding the theoretical limit, reaching 20.43% and 21.41% respectively. In addition, the two color white OLED with Ir3 as the blue emitter also achieves an extremely high device efficiency, having a maximum EQE of up to 20.17% The excellent blue emission and high device efficiency indicates that the four phosphors have huge potential applications for high performance blue and white phosphorescent OLEDs.
author_names: Yanqin Miao

Peng Tao

Long Gao

Xiangling Li

Liuwei Wei

Shujuan Liu

Hua Wang

Bingshe Xu

Qiang Zhao
title: Highly efficient chlorine functionalized blue iridium(III) phosphors for blue and white phosphorescent organic light emitting diodes with the external quantum efficiency exceeding 20%
year: 2018

abstract: Triarylboron compounds have attracted much attention, and found wide use as functional materials because of their electron accepting properties arising from the vacant p orbitals on the boron atoms. In this study, we design and synthesize new donor acceptor triarylboron emitters that show thermally activated delayed fluorescence. These emitters display sky blue to green emission and high photoluminescence quantum yields of 87 100 in host matrices. Organic light emitting diodes using these emitting molecules as dopants exhibit high external quantum efficiencies of 14.0 22.8 which originate from efficient up conversion from triplet to singlet states and subsequent efficient radiative decay from singlet to ground states.
author_names: Katsuaki Suzuki

Shosei Kubo

Katsuyuki Shizu

Tatsuya Fukushima

Atsushi Wakamiya

Yasujiro Murata

Chihaya Adachi

Hironori Kaji
title: Triarylboron Based Fluorescent Organic Light Emitting Diodes with External Quantum Efficiencies Exceeding 20
venue: Angewandte Chemie
year: 2015

abstract: Metal halide perovskites have received considerable attention in the field of electroluminescence, and the external quantum efficiency of perovskite light emitting diodes has exceeded 20% CH 3 NH 3 PbBr 3 has been intensely investigated as an emitting layer in perovskite light emitting diodes. However, perovskite films comprising CH 3 NH 3 PbBr 3 often exhibit low surface coverage and poor crystallinity, leading to high current leakage, severe nonradiative recombination, and limited device performance. Herein, we demonstrate a rationale for composition engineering to obtain high quality perovskite films. We first reduce pinholes by adding excess CH 3 NH 3 Br to the actual CH 3 NH 3 PbBr 3 films, and we then add CsBr to improve the crystalline quality and to passivate nonradiative defects. As a result, the (CH 3 NH 3 1 x Cs x PbBr 3 based perovskite light emitting diodes exhibit significantly improved external quantum and power efficiencies of 6.97% and 25.18 lm/W, respectively, representing an improvement in performance dozens of times greater than that of pristine CH 3 NH 3 PbBr 3 based perovskite light emitting diodes. Our study demonstrates that composition engineering is an effective strategy for enhancing the device performance of perovskite light emitting diodes.
author_names: Chuanzhong Yan

Kebin Lin

Jianxun Lu

Zhanhua Wei
title: Composition engineering to obtain efficient hybrid perovskite light emitting diodes
year: 2020

abstract: Metal halide perovskites are promising candidates for use in light emitting diodes (LEDs) due to their potential for color tunable and high luminescence efficiency. While recent advances in perovskite based light emitting diodes have resulted in external quantum efficiencies exceeding 12.4% for the green emitters, and infrared emitters based on 3 D/2D mixed dimensional perovskites have exceeded 20% the external quantum efficiencies of the red and blue emitters still lag behind. A critical issue to date is creating highly emissive and stable perovskite emitters with the desirable emission band gap to achieve full color displays and white LEDs. Herein, we report the preparation and characterization of a highly luminescent and stable suspension of cubic shaped methylammonium lead triiodide (CH3NH3PbI3) perovskite nanocrystals, where we synthesize the nanocrystals via a ligand assisted reprecipitation technique, using an acetonitrile/methylamine compound solvent system to solvate the ions and toluene as the antisolvent to induce crystallization. Through tuning the ratio of the ligands, the ligand to toluene ratio, and the temperature of the toluene, we obtain a solution of CH3NH3PbI3 nanocrystals with a photoluminescence quantum yield exceeding 93% and tunable emission between 660 and 705 nm. We also achieved red emission at 635 nm by blending the nanocrystals with bromide salt and obtained perovskite based light emitting diodes with maximum electroluminescent external quantum efficiency of 2.75%
author_names: Yasser Hassan

Olivia J Ashton

Jong Hyun Park

Guangru Li

Nobuya Sakai

Bernard Wenger

Amir A Haghighirad

Nakita K Noel

Myoung Hoon Song

Bo Ram Lee

Richard H Friend

Henry J Snaith
title: Facile Synthesis of Stable and Highly Luminescent Methylammonium Lead Halide Nanocrystals for Efficient Light Emitting Devices.
venue: Journal of the American Chemical Society
year: 2019

abstract: Perovskite light emitting diodes (PeLEDs) have showed significant progress in recent years; the external quantum efficiency (EQE) of electroluminescence in green and red regions has exceeded 20% but the efficiency in blue lags far behind. Here, a large cation CH3CH2NH2+ is added in PEA2(CsPbBr3)2PbBr4 perovskite to decrease the Pb Br orbit coupling and increase the bandgap for blue emission. X ray diffraction and nuclear magnetic resonance results confirmed that the EA has successfully replaced Cs+ cations to form PEA2(Cs1 xEAxPbBr3)2PbBr4. This method modulates the photoluminescence from the green region (508 nm) into blue (466 nm) and over 70% photoluminescence quantum yield in blue is obtained. In addition, the emission spectra is stable under light and thermal stress. With configuration of PeLEDs with 60% EABr, as high as 12.1% EQE of sky blue electroluminescence located at 488 nm has been demonstrated, which will pave the way for the full color display for the PeLEDs. Blue light emitting diodes (LEDs) are critical for displays. Employing a large organic cation into a quasi two dimensional perovskite with green emission, Chu et al. achieve LEDs exhibiting a high external quantum efficiency of 12.1% and stable spectra in the sky blue region.
author_names: Zema Chu

Yang Zhao

Fei Ma

Cai-Xin Zhang

Huixiong Deng

Fengli Gao

Qiufeng Ye

Junhua Meng

Zhigang Yin

Xingwang Zhang

Jingbi You
title: Large cation ethylammonium incorporated perovskite for efficient and spectra stable blue light emitting diodes
venue: Nature Communications
year: 2020