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Halide perovskite quantum dots: potential candidates for display technology

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Science Bulletin 2015年第18期60卷 1622-1624页

作者： Zelong Bai Haizheng zhong Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of Materials Science and Engineering Beijing Institute of Technology

Motivated by the color tunability and narrow-band emission peak of colloidal quantum dots(QDs),the concepts of quantum dot light-emitting diodes(QD-LEDs),based on either the photoluminescence(PL)or electroluminescence(EL)mechanism,have been proposed for a few years[1].Using QD-LEDs in the backlighting system of liquid crystal display(LCD)can significantly expand the

关键词：显示技术量子点钙钛矿型电致发光器件发光二极管背光照明系统液晶显示器光致发光

Perovskite quantum dot microarrays:In situ fabrication via direct print photopolymerization

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Nano Research 2022年第8期15卷 7681-7687页

作者： Xiu Liu Jianjun Li Pingping Zhang Weitong Lu Gaoling Yang Haizheng zhong Yuejin Zhao School of Optics and Photonics Beijing Institute of TechnologyBeijing 100081China MIIT Key Laboratory for Low Dimensional Quantum Structure and Devices School of Materials Sciences&EngineeringBeijing Institute of TechnologyBeijing 100081China MIIT Key Laboratory for Low Dimensional Quantum Structure and Devices Beijing 100081China

Quantum dots color conversion(QDCC)is considered as a facial and versatile way to achieve full-color organic light emitting diode(OLED)and micro-LED display due to the wide color gamut performance and easy integration.However,the aggregation of QDs and coffee-ring effects after solvent evaporation lowers the light conversion efficiency and emission uniformity in QDs microarrays,raising blue-light leakage or optical crosstalk.Here,we report the fabrication of perovskite quantum dots(PQDs)microarrays by combining the inkjet printing and in situ fabrication of PQDs during the photopolymerization of precursor ink.The resulting PQDs microarrays exhibit three-dimensional(3D)morphology with hemisphere shape as well as strong photoluminescence,which is desirable for QDCC applications.We demonstrate the dominant role of ultraviolet(UV)curable precursors and surface functionalized substrate in controlling the shape of microarrays,where significantly increased contact angle(100°)and large height to diameter ratio(0.42)can be achieved.We further demonstrate the potential use of the in situ direct print photopolymerization method for fabricating large-area multicolor patterned pixel microarrays with a wide color gamut and high resolution.The fabrication of 3D PQDs microarrays opens up new opportunities in a variety of applications including photonics integration,micro-LED,and near-field display.

关键词： quantum dots perovskite in situ fabrication inkjet printing microarrays

Revealing the vertical structure of in-situ fabricated perovskite nanocrystals films toward efficient pure red light-emitting diodes

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Fundamental Research 2024年第2期4卷 362-368页

作者： Xian-gang Wu Shipei Sun Tinglu Song Xin Zhang Chenhui Wang Yingguo Yang Shuangpeng Wang Haizheng zhong MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices School of Materials Science&EngineeringBeijing Institute of TechnologyBeijing 100081China Experimental Center of Advanced Materials School of Materials Science&EngineeringBeijing Institute of TechnologyBeijing 100081China Shanghai Synchrotron Radiation Facility(SSRF) Shanghai Institute of Applied PhysicsChinese Academy of SciencesShanghai 201204China Institute of Applied Physics and Materials Engineering University of MacaoMacao 999078China

The development of efficient perovskite light-emitting diodes(PeLEDs)relies strongly on the fabrication of perovskite films with rationally designed structures(grain size,composition,surface,etc.).Therefore,an understanding of structure-performance relationships is of vital importance for developing high-performance perovskite devices,particularly for devices with in-situ fabricated perovskite nanocrystal films.In this study,we reveal the vertical structure of an in-situ fabricated quasi-two-dimensional perovskite film.By combining time-of-flight secondary ion mass spectrometry,energy dispersive spectroscopy,grazing incidence wide-angle X-ray scattering(GIWAXS),and low-temperature photoluminescence spectra,we illustrate that the resulting in-situ fabricated DPPA_(2)Cs_(n-1)Pb_(n)(Br_(0.3)I_(0.7))_(3n+1)(DPPA^(+):3,3-diphenylpropylammonium)film has a gradient structure with a very thin layer of ligands on the surface,predominantly small-n domains at the top,and predominantly large-n domains at the bottom owing to the solubility difference of the precursors.In addition,GIWAXS measurements show that the domain of n=2 on the top layer has an ordered in-plane alignment.Based on the understanding of the film structure,we developed an in-situ fabrication process with ligand exchange to achieve efficient pure red PeLEDs at 638 nm with an average external quantum efficiency(EQE)of 7.4%.The optimized device had a maximum luminance of 623 cd/m^(2) with a peak EQE of 9.7%.

关键词： Light-emitting diodes Perovskite TOF-SIMS Vertical structure in-situ fabrication

Broadband perovskite quantum dot spectrometer beyond human visual resolution

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Light(Science & Applications) 2020年第1期9卷 1329-1337页

作者： Xiaoxiu Zhu Liheng Bian Hao Fu Lingxue Wang Bingsuo Zou Qionghai Dai Jun Zhang Haizheng zhong MIIT Key Laboratory for Low-dimensional Quantum Structure and Devices Beijing Institute of Technology100081 BeijingChina School of Materials Science&Engineering Beijing Institute of Technology100081 BeijingChina School of Information and Electronics&Advanced Research Institute of Multidisciplinary Science Beijing Institute of Technology100081 BeijingChina Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of Optics and PhotonicsBeijing Institute of Technology100081 BeijingChina Department of Automation&School of Information Science and Technology Tsinghua University100086 BeijingChina Beijing National Research Center for Information Science and Technology 100086 BeijingChina

The quantum dot spectrometer,fabricated by integrating different quantum dots with an image sensor to reconstruct the target spectrum from spectral-coupled measurements,is an emerging and promising hyperspectrometry technology with high resolution and a compact size.The spectral resolution and spectral range of quantum dot spectrometers have been limited by the spectral variety of the available quantum dots and the robustness of algorithmic reconstruction.Moreover,the spectrometer integration of quantum dots also suffers from inherent photoluminescence emission and poor batch-to-batch repeatability.In this work,we developed nonemissive in situ fabricated MA_(3)Bi_(2)X_(9) and Cs_(2)SnX_(6)(MA=CH_(3)NH_(3);X=Cl,Br,I)perovskite-quantum-dot-embedded films(PQDFs)with precisely tunable transmittance spectra for quantum dot spectrometer applications.The resulting PQDFs contain in situ fabricated perovskite nanocrystals with homogenous dispersion in a polymeric matrix,giving them advantageous features such as high transmittance efficiency and good batch-to-batch repeatability.By integrating a filter array of 361 kinds of PQDFs with a silicon-based photodetector array,we successfully demonstrated the construction of a perovskite quantum dot spectrometer combined with a compressive-sensing-based total-variation optimization algorithm.A spectral resolution of ~1.6 nm was achieved in the broadband of 250-1000 nm.The performance of the perovskite quantum dot spectrometer is well beyond that of human eyes in terms of both the spectral range and spectral resolution.This advancement will not only pave the way for using quantum dot spectrometers for practical applications but also significantly impact the development of artificial intelligence products,clinical treatment equipment,scientific instruments,etc.

关键词： quantum perovskite batch

Breaking the symmetry of colloidal 2D nanoplatelets:Twist induced quantum coupling

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Nano Research 2023年第7期16卷 10522-10529页

作者： Zahid Nazir Yingzhuo Lun Jialu Li Gaoling Yang Mingrui Liu Shuqi Li Gang Tang Guofeng Zhang Jiawang Hong Liantuan Xiao Haizheng zhong MIIT Key Laboratory for Low-dimensional Quantum Structure and Devices School of Materials Science&EngineeringBeijing Institute of TechnologyBeijing 100081China MIIT Key Laboratory for Low-dimensional Quantum Structure and Devices School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Laser SpectroscopyCollaborative Innovation Center of Extreme OpticsShanxi UniversityTaiyuan 030006China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China

Twist provides a new degree of freedom for nanomaterial modifications,which can provide novel physical properties.Here,colloidal two-dimensional(2D)twisted CdSe nanoplatelets(NPLs)are successfully fabricated and their morphology can change from totally flat to edge-twisted,and then to middle-twisted with prolonged reaction time.By combining experiments and corresponding theoretical analyses,we have established the length-dependent relationships between the surface energy and twist,with a critical lateral dimension of 30 nm.We found that the defects formed during the synthesis process play a vital role in generating intense stress that develops a strong torsion tensor around the edges,resulting in edge-twisted and final middletwisted NPLs.Furthermore,due to the geometric asymmetry of twisted NPLs,the dissymmetry factor of single particle NPLs can reach up to 0.334.Specifically,quantum coupling occurs in middle-twisted NPLs by twisting one parent NPL into two daughter NPLs,which are structurally and electronically coupled.This work not only further deepens our understanding of the twist mechanism of 2D NPLs during colloidal synthesis,but also opens a pathway for applications using twistronics and quantum technology.

关键词： nanoplatelets CdSe twist circular dichroism quantum coupling

Luminescent Nanocomposites Incorporated with Quantum Dots for Light-emitting and Display Applications

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Luminescent Nanocomposites Incorporated with Quantum Dots fo...

Lensless opto-electronic neural network with quantum dot nonlinear activation

中国化学会第29届学术年会

作者： Haizheng zhong Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of Materials Science ＆ EngineeringBeijing Institute of Technology

Colloidal semiconductor nanocrystals have been widely studied due to their size-dependent optical properties as well as the potential applications in the field of optic s and optoelectronics. To develop these applications, there is an increased need to embed them into transparent matrix. The as-prepared nanocomposite materials show great promise as they can provide the necessary stability and processability for these im portant applications. However, preparation of lar ge size, high transparent and highly lum inescent QDs based nanocom posites is still a great challenge due to well-known ligand exchange induced PL quenching effects and aggregation induced scattering. We recently developed high quality nanocyrstals（CuInS2 QDs and CdxZn1-xTe QDs）, and worked on the surface and interface engineering to incorporate these luminescen t nanocrystals into transp arent matrices and studied the applications in light-emitting diodes and 3D display applications.

关键词： quantum dots,semiconductor nanocrystals nanocomposite optics

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Photonics Research 2024年第4期12卷 682-690页

作者： WANXIN SHI XI JIANG ZHENG HUANG XUE LI YUYANG HAN SIGANG YANG Haizheng zhong HONGWEI CHEN Beijing National Research Center for Information Science and Technology(BNRist) Department of Electronic EngineeringTsinghua University China Mobile Research Institute MIIT Key Laboratory for Low-dimensional Quantum Structure and Devices School of Materials Sciences & EngineeringBeijing Institute of Technology

With the swift advancement of neural networks and their expanding applications in many fields, optical neural networks have gradually become a feasible alternative to electrical neural networks due to their parallelism, high speed, low latency, and power consumption. Nonetheless, optical nonlinearity is hard to realize in free-space optics, which restricts the potential of the architecture.

关键词： Free space optics Lithium niobate waveguides Neural networks Optical neural systems Spatial light modulators Vertical cavity surface emitting lasers

Erratum to:Highly efficient and stable white LEDs based on pure red narrow bandwidth emission triangular carbon quantum dots for wide-color gamut backlight displays

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Nano Research 2020年第8期13卷 2309-2310页

作者： Fanglong Yuan Ping He Zifan Xi Xiaohong Li Yunchao Li Haizheng zhong Louzhen Fan Shihe Yang College of Chemistry Beijing Normal UniversityBeijing100875China Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of Materials Science and Engineering Beijing Institute of TechnologyBeijing100081China Guangdong Key Lab of Nano-Micro Material Research School of Chemical Biology and BiotechnologyShenzhen Graduate SchoolPeking UniversityShenzhen518055China

In the version of this article originally published,Figs.2(d)and 3(a),and Figs.S3 and S6 in the Electronic Supplementary Material(ESM)were incorrect.The corrected images are shown below.

关键词： narrow Highly triangular

In-situ fabricated anisotropic halide perovskite nanocrystals in polyvinylalcohol nanofibers: Shape tuning and polarized emission

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Nano Research 2019年第6期12卷 1411-1416页

作者： Linghai Meng Changgang Yang Jingjia Meng Yongzhi Wang Yong Ge Ziqiang Shao Guofeng Zhang Andrey L.Rogach Haizheng zhong Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Beijing Engineering Research Center of Cellulose and Its Derivatives School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing H 100081China State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Laser SpectroscopyShanxi UniversityTaiyuan 030006China Department of Materials Science and Engineering and Centre for Functional Photonics (CFP)City University of Hong KongHong Kong 999077China

We report an in-situ fabrication of halide perovskite (CH3NH3PbX3,CH3NH3 =methylammonium,MA,X =Cl,Br,I) nanocrystals in polyvinylalcohol (PVA) nanofibers (MAPbX3@PVA nanofibers) through electrospinning a perovskite precursor solution.With the content of the precursors increased,the resulting MAPbBr3 nanocrystals in PVA matrix changed the shape from ellipsoidal to pearl-like,and finely into rods-like.Optimized MAPbBr3@PVA nanofibers show strong polarized emission with the photoluminescence quantum yield of up to 72%.We reveal correlations between the shape of in-situ fabricated perovskite nanocrystals and the polarization degree of their emission by comparing experimental data from the single nanofiber measurements with theoretical calculations.Polarized emission of MAPbBr3@PVA nanofibers can be attributed to the dielectric confinement and quantum confinement effects.Moreover,nanofibers can be efficiently aligned by using parallel positioned conductor strips with an air gap as collector.A polarization ratio of 0.42 was achieved for the films of well-aligned MAPbBr3@PVA nanofibers with a macroscale size of 0.5 cm × 2 cm,which allows potential applications in displays,lasers,waveguides,etc.

关键词： lead halide perovskite nanofibers electrospinning anisotropy polarized emission