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1.
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The flexible perovskite light-emitting diodes (FPeLEDs), which can be expediently integrated to portable and wearable devices, have shown great potential in various applications. The FPeLEDs inherit the unique optical properties of metal halide perovskites, such as tunable bandgap, narrow emission linewidth, high photoluminescence quantum yield, and particularly, the soft nature of lattice. At present, substantial efforts have been made for FPeLEDs with encouraging external quantum efficiency (EQE) of 24.5%. Herein, we summarize the recent progress in FPeLEDs, focusing on the strategy developed for perovskite emission layers and flexible electrodes to facilitate the optoelectrical and mechanical performance. In addition, we present relevant applications of FPeLEDs in displays and beyond. Finally, perspective toward the future development and applications of flexible PeLEDs are also discussed.  相似文献   

2.
    
Core/shell structured metal halide perovskite nanocrystals (NCs) are emerging as a type of material with remarkable optical and electronic properties. Research into this field has been developing and expanding rapidly in recent years, with significant advances in the studies of the shell growth mechanism and in understanding of properties of these materials. Significant enhancement of both the stability and the optical performance of core/shell perovskite NCs are of particular importance for their applications in optoelectronic technologies. In this review, the recent advances in core/shell structured perovskite NCs are summarized. The band structures and configurations of core/shell perovskite NCs are elaborated, the shell classification and shell engineering approaches, such as perovskites and their derivative shells, semiconductor shell, oxide shell, polymer shell, etc. are reviewed, and the shell growth mechanisms are discussed. The prospective of these NCs in lighting and displays, solar cells, photodetectors, and other devices is discussed in the light of current knowledge, remaining challenges, and future opportunities.  相似文献   

3.
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In backlighting systems for liquid crystal displays,conventional red,green,and blue(RGB)light sources that lack polariz-ation properties can result in a significant optical loss of up to 50%when passing through a polarizer.To address this in-efficiency and optimize energy utilization,this study presents a high-performance device designed for RGB polarized emissions.The device employs an array of semipolar blue μLEDs with inherent polarization capabilities,coupled with mechanically stretched films of green-emitting CsPbBr3 nanorods and red-emitting CsPbI3-Cs4PbI6 hybrid nanocrystals.The CsPbBr3 nanorods in the polymer film offer intrinsic polarization emission,while the aligned-wire structures formed by the stable CsPbI3-Cs4PbI6 hybrid nanocrystals contribute to substantial anisotropic emissions,due to their high dielec-tric constant.The resulting device achieved RGB polarization degrees of 0.26,0.48,and 0.38,respectively,and exhib-ited a broad color gamut,reaching 137.2%of the NTSC standard and 102.5%of the Rec.2020 standard.When com-pared to a device utilizing c-plane LEDs for excitation,the current approach increased the intensity of light transmitted through the polarizer by 73.6%.This novel fabrication approach for polarized devices containing RGB components holds considerable promise for advancing next-generation display technologies.  相似文献   

4.
    
Recently, all‐inorganic cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals have drawn much attention because of their outstanding photophysical properties and potential applications. In this work, a simple and efficient solvothermal approach to prepare CsPbX3 nanocrystals with tunable and bright photoluminescent (PL) properties, controllable composition, and morphology is presented. CsPbX3 nanocubes are successfully prepared with bright emission high PL quantum yield up to 80% covering the full visible range and narrow emission line widths (from 12 to 36 nm). More importantly, ultrathin CsPbX3 (X = Cl/Br, Br, and Br/I) nanowires (with diameter as small as ≈2.6 nm) can be prepared in a very high morphological yield (almost 100%). A strong quantum confinement effect is observed in the ultrathin nanowires, in which both the absorption and emission peaks shift to shorter wavelength range compared to their bulk bandgap. The reaction parameters, such as temperature and precursors, are varied to investigate the growth process. A white light‐emitting device prototype device with wide color gamut covering up to 120% of the National Television System Committee standard has been demonstrated by using CsPbBr3 nanocrystals as the green light source. The method in this study provides a simple and efficient way to prepare high‐quality CsPbX3 nanocrystals.  相似文献   

5.
采用第一性原理计算,研究了有机金属卤化物钙钛矿CH3NH3PbI3和CH3NH3MnI3的电子结构、磁性和光吸收。CH3NH3PbI3和CH3NH3MnI3都是具有直接带隙半导体,CH3NH3MnI3磁基态为G型反铁磁序（G-AFM）。CH3NH3MnI3在G-AFM状态下的带隙值为1.668 eV;当系统处于FM态时,多数自旋通道的带隙为0.696 eV,少数自旋通道的带隙为2.148 eV。结果表明,具有FM态的CH3NH3MnI3的光激发电子将迅速熔化局域磁序。最后计算了CH3NH3PbI3和CH3NH3MnI3的光学特性,结果表明具有铁磁态的CH3NH3MnI3（FM）表现出较强的红外光吸收。  相似文献   

6.
    
Self-assembly of nanocrystals into controlled structures while uncompromising their properties is one of the key steps in optoelectronic device fabrication. Herein, zigzag CsPbBr3 perovskite nanocrystals are demonstrated with a precise number of components with nanocube morphology, these can be successfully obtained through a dipole-induced self-assembly process. The addition of a trace amount of deionized water facilitates the transfer from CsPbBr3 nanocubes to intermediates of CsPb2Br5 and Cs3In2Br9, which then fastly release reaction monomers leading to further homogenous nucleation of CsPbBr3 nanocubes, followed by the formation of zigzag CsPbBr3 nanocrystals through a dipole-induced self-assembly process. Dipole moment along <110> axis is found to be the driving force for the assembly of nanocubes into zigzag nanocrystals. The zigzag CsPbBr3 nanocrystals exhibit desirable optical properties comparable to their nanocube counterparts and offer advantages for amplified spontaneous emission and lasing applications with low pump thresholds of 3.1 and 6.02 µJ cm−2, respectively. This study not only develops a strategy for producing highly controlled zigzag perovskite nanocrystals and provides insights on the dipole-induced self-assembly mechanisms, but also opens an avenue for their application in lasing.  相似文献   

7.
    
Lead halide perovskite nanocrystals (LHP-NCs) incorporated within polymer matrices have emerged as promising materials for various photonic applications. However, challenges persist in achieving high-quality nanocomposites due to low monomer conversion yields, restricted LHP-NCs loadings, and difficulty in maintaining NCs integrity post-polymerization. A novel protocol for synthesizing LHP-NCs/poly(methyl methacrylate) nanocomposites in a single step via the NC-initiated photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) method is presented. Polymerization initiation mediated by NCs surfaces under blue light enables the fabrication of homogeneous nanocomposites with NCs loadings up to 7% w/w and ≈90% monomer conversion even in the presence of oxygen. This process preserves the optical quality of the NCs and passivates NCs surface defects, resulting in nanocomposites exhibiting near unity luminescence efficiencies. The potential of this approach for producing highly loaded nanocomposites for radiation detection is validated by radioluminescence measurements showing light yield values of 6000 ph MeV−1 and fast scintillation dynamics with effective lifetime of 490 ps, showing promise for time-of-flight radiometry.  相似文献   

8.
    
Structuring metal halide perovskites with mixed halide anions is a promising strategy for attaining the desired bandgap and emission color for technological applications such as electroluminescent (EL) light-emitting diodes (LEDs) and ultrahigh-definition displays. However, these mixed halide perovskites suffer from severe EL spectral stability issues. During device operation, homogeneously mixed halide perovskite phases are prone to form halide-segregated domain phases with spatially inhomogeneous bandgap and emission color, which hinders practical use of perovskite LEDs (PeLEDs). In this review, a comprehensive survey is performed about the underlying driving forces for phase segregation, and representative strategies are discussed for the development of color/spectral stable mixed halide PeLEDs. Finally, the future directions and prospects are outlined regarding further enhancement of the color/spectral stability of mixed halide PeLEDs.  相似文献   

9.
    
Perovskite light‐emitting diodes (LEDs) require small grain sizes to spatially confine charge carriers for efficient radiative recombination. As grain size decreases, passivation of surface defects becomes increasingly important. Additionally, polycrystalline perovskite films are highly brittle and mechanically fragile, limiting their practical applications in flexible electronics. In this work, the introduction of properly chosen bulky organo‐ammonium halide additives is shown to be able to improve both optoelectronic and mechanical properties of perovskites, yielding highly efficient, robust, and flexible perovskite LEDs with external quantum efficiency of up to 13% and no degradation after bending for 10 000 cycles at a radius of 2 mm. Furthermore, insight of the improvements regarding molecular structure, size, and polarity at the atomic level is obtained with first‐principles calculations, and design principles are provided to overcome trade‐offs between optoelectronic and mechanical properties, thus increasing the scope for future highly efficient, robust, and flexible perovskite electronic device development.  相似文献   

10.
    
The poor stability of CsPbX3 (X = Cl, Br, I) perovskite quantum dots (PQDs) in polar solvents such as water, seriously hinders their practical application. Herein, 5-Bromovaleric acid (BVA) is used to replace oleic acid (OA), the most common surface ligand in CsPbX3 PQDs synthesis. Under the synergic action of oleylamine (OLA), CsPbX3 PQDs with high water stability can be synthesized directly in water. Because the carboxyl ligands provided by BVA, and the long chain amines provided by OLA formed hydrophobic shells on the surface of CsPbBr3 PQDs, the obtained CsPbBr3 PQDs still has high luminescence intensity and photoluminescence quantum yield after being dispersed in water for several days, and the luminescence peak is always maintained at 518 nm. In contrast, the luminescence intensity of CsPbBr3 PQDs synthesized with OA and OLA is <1% of the initial intensity after only 30 min. CsPbCl3 and CsPbI3 PQDs synthesized directly in water by this method also show high water stability. In this study, for the first time the synthesis method of CsPbX3 PQDs with high water stability using BVA/OLA as surface ligands is proposed, which provides an effective way to explore the synthesis of PQDs that can maintain stability in water.  相似文献   

11.
    
Lead halide perovskite nanocrystals (PeNCs) are promising materials for applications in optoelectronics. However, their environmental instability remains to be addressed to enable their advancement into industry. Here the development of a novel synthesis method is reported for monodispersed PeNCs coated with all inorganic shell of cesium lead bromide (CsPbBr3) grown epitaxially on the surface of formamidinium lead bromide (FAPbBr3) NCs. The formed FAPbBr3/CsPbBr3 NCs have photoluminescence in the visible range 460–560 nm with narrow emission linewidth (20 nm) and high optical quantum yield, photoluminescence quantum yield (PLQY) up to 93%. The core/shell perovskites have enhanced optical stability under ambient conditions (70 d) and under ultraviolet radiation (50 h). The enhanced properties are attributed to overgrowth of FAPbBr3 with all‐inorganic CsPbBr3 shell, which acts as a protective layer and enables effective passivation of the surface defects. The use of these green‐emitting core/shell FAPbBr3/CsPbBr3 NCs is demonstrated in light‐emitting diodes (LEDs) and significant enhancement of their performance is achieved compared to core only FAPbBr3‐LEDs. The maximum current efficiency observed in core/shell NC LED is 19.75 cd A‐1 and the external quantum efficiency of 8.1%, which are approximately four times and approximately eight times higher, respectively, compared to core‐only devices.  相似文献   

12.
    
Interfaces between the photoactive and charge transport layers are crucial for the performance of perovskite solar cells. Surface passivation of SnO2 as electron transport layer (ETL) by fullerene derivatives is known to improve the performance of n–i–p devices, yet organic passivation layers are susceptible to removal during perovskite deposition. Understanding the nature of the passivation is important for further optimization of SnO2 ETLs. X‐ray photoelectron spectroscopy depth profiling is a convenient tool to monitor the fullerene concentration in passivation layers at a SnO2 interface. Through a comparative study using [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) and [6,6]‐phenyl‐C61‐butyric acid (PCBA) passivation layers, a direct correlation is established between the formation of interfacial chemical bonds and the retention of passivating fullerene molecules at the SnO2 interface that effectively reduces the number of defects and enhances electron mobility. Devices with only a PCBA‐monolayer‐passivated SnO2 ETL exhibit significantly improved performance and reproducibility, achieving an efficiency of 18.8%. Investigating thick and solvent‐resistant C60 and PCBM‐dimer layers demonstrates that the charge transport in the ETL is only improved by chemisorption of the fullerene at the SnO2 surface.  相似文献   

13.
    
Deterministic integration of arbitrary semiconductor heterostructures opens a new class of modern electronics and optoelectronics. However, the realization of such heterostructures continues to suffer from impracticality, requiring energy- and labor-intensive, time-consuming fabrication processes. Here a 3D printing approach to fabricate freestanding metal halide perovskite nanowire heterostructures with a high degree of control over shape and composition is demonstrated. These features arise from freeform guiding of evaporation-driven perovskite crystallization by a femtoliter precursor meniscus formed on a printing nozzle. By using a double-barreled nanopipette as a printing nozzle, “all-at-once” heterostructure fabrication is achieved within seconds. The 3D-printed perovskite nanowire heterojunctions with multiple emission colors provide exciting optical functionalities such as programmable color mixing and encryption at the single nanopixel level. This “lithography-free” additive approach opens up the possibility to freely design and realize heterostructure-based devices without the constraints of traditional manufacturing processes.  相似文献   

14.
    
Recently, lead halide perovskite (PVSK) polycrystalline films have drawn much attention as photoactive material and scored tremendous achievements in solar cells, photodetectors, light-emitting diodes, and lasers owing to their engrossing optoelectronic properties and facile solution-processed fabrication. However, large amounts of grain boundaries unfavorably induce ion migration, surface defect, and poor stability, impeding PVSK polycrystalline film-based optoelectronic devices from practical application. In comparison with the polycrystalline counterparts, PVSK single crystals (SCs) with lower trap density serve as a better platform for not only fundamental research but also device applications. In light of this, the idea of using PVSK single crystals (SCs) to construct the optoelectronic devices is then proposed. Since then, a series of synthesis methods of PVSK SCs have emerged. In this review, recent progress of synthesis method of PVSK SCs is tried to be summarized and their advantages and limitations are analyzed. And then, the optoelectronic properties including carrier dynamic, defects, ion migration, and instability issues in these 3D and 2D PVSK SCs are overviewed and accordingly the proper device configurations of corresponding solar cells, photodetectors, X-ray, γ-ray detectors, etc., are proposed. It is believed that this review can provide the guidance for the further development of PVSK SCs and their applications.  相似文献   

15.
    
Bismuth (Bi3+)-included lead-free metal halide (LFMH) materials attract much attention in lighting, display, photodetectors, X-ray detectors, and photovoltaic fields, due to the tunable luminescence and optoelectronic performance in response to crystal and electronic structure, morphology, and particle sizes. This review summarizes Bi3+-included LFMH materials about their preparation approach, crystal and electronic structure properties, luminescence performance, and emerging applications. Notably, Bi3+ ions not only can act as framework cation to construct stable LFMH structure, but can also incorporate into LFMH materials as activators or sensitizers to generate remarkable luminescence tuning and band engineering. The Bi3+ effect on the luminescence and optoelectronic properties of LFMH materials, including, promotion of exciton localization, enhancement of light absorption in near-ultraviolet region, action as sensitizer ions to transfer energy to rare earth or transition metal ions and emission of highly-efficient light is systematically summarized. The proposed structure-luminescence relationship offers guidance for the optimization of current Bi3+-included LFMH materials and the exploitation of new LFMH derivatives.  相似文献   

16.
    
3D organic–inorganic lead halide perovskites have shown great potential in efficient photovoltaic devices. However, the low stability of the 3D perovskite layer and random arrangement of the perovskite crystals hinder its commercialization road. Herein, a highly oriented 2D@3D ((AVA)2PbI4@MAPbI3) perovskite structure combining the advantages of both 2D and 3D perovskite is fabricated through an in situ route. The highest power conversion efficiency (PCE) of 18.0% is observed from a 2D@3D perovskite solar cell (PSC), and it also shows significantly enhanced device stability under both inert (90% of initial PCE for 32 d) and ambient conditions (72% of initial PCE for 20 d) without encapsulation. The high efficiency of 18.0% and nearly twofold improvement of device stability in ambient compared with pure 3D PSCs confirm that such 2D@3D perovskite structure is an effective strategy for high performance and increasing stability and thus will enable the timely commercialization of PSCs.  相似文献   

17.
    
Despite significant advances in iron oxide nanoparticles, it is still a challenge to synthesize regular polyhedral single‐crystalline α‐Fe2O3 particles because the surface energies of several low‐index planes are fairly similar. In the work presented here, well‐dispersed and single‐crystalline dodecahedral and octodecahedral α‐Fe2O3 particles are synthesized by a facile hydrothermal method with the aid of F? anions. The crystalline structure of the polyhedral particles is disclosed by various characterization techniques. The dodecahedral particles are of hexagonal bipyramidal shape and enclosed by twelve equivalent (101) planes. The octodecahedral particles are formed by adding six equivalent (111) planes on the two tips of a dodecahedral particle, that is, they are enclosed by twelve (101) planes and six (111) planes. The existence of F? anions plays a crucial role in the control of polyhedral particle shape. The function of F? anions in the shape formation of the polyhedral particles is proposed as follows: 1) A high concentration of exposed Fe3+ cations induces preferential adsorption of F? anions on the (100) plane and leads to the slowest growth along the [100] direction. When the concentration of F? anions is higher than 24 mM , a stable speed ratio of growth along the [001] and [100] directions results in the exposure of (101) planes. 2) With a lower concentration of F? anions, six symmetrical (111) planes with low concentration of exposed Fe3+ cations are present at the tops of a dodecahedral particle to form an octodecahedron. Furthermore, the dodecahedral and octodecahedral α‐Fe2O3 particles show much stronger magnetism than the previously reported α‐Fe2O3 nanostructures, having coercivities of 4986 Oe and 6512 Oe, respectively. Such high coercivities are attributed to a large local magnetic anisotropy, which might be induced by the polyhedron with equivalent crystallographic planes and/or the presence of F? anions.  相似文献   

18.
    
Inorganic semiconductor arrays revolutionize many areas of electronics, optoelectronics with the properties of multifunctionality and large-scale integration. Metal halide perovskites are emerging as candidates for next-generation optoelectronic devices due to their excellent optoelectronic properties, ease of processing, and compatibility with flexible substrates. To date, a series of patterning technologies have been applied to perovskites to realize array configurations and nano/microstructured surfaces to further improve device performances. Herein, various construction methods for perovskite crystal or thin film arrays are summarized. The optoelectronic applications of the perovskite arrays are also discussed, in particular, for photodetectors, light-emitting diodes, lasers, and nanogratings.  相似文献   

19.
    
Metal halide perovskites are promising materials for optoelectronic and photonic applications ranging from photovoltaics to laser devices. However, current perovskite devices are constrained to simple low-dimensional structures suffering from limited design freedom and holding up performance improvement and functionality upgrades. Here, a micro-origami technique is developed to program 3D perovskite microarchitectures toward a new type of microcavity laser. The design flexibility in 3D supports not only outstanding laser performance such as low threshold, tunable output, and high stability but also yields new functionalities like 3D confined mode lasing and directional emission in, for example, laser “array-in-array” systems. The results represent a significant step forward toward programmable microarchitectures that take perovskite optoelectronics and photonics into the 3D era.  相似文献   

20.
    
Halide perovskite semiconductors find use in a broad range of optoelectronic applications including photovoltaic solar cells and light-emitting diodes. In such devices the semiconductor is sandwiched in between interlayers for charge transport, extraction, or injection. When it comes to hole transport layers, the conducting polymer PEDOT:PSS has become an ubiquitous material. The halide perovskite thin film is commonly obtained by crystallization of precursors using solution processing on top of PEDOT:PSS. It is demonstrated here that such a widely spread technique is actually affecting the electrical properties of the underlying conducting polymer. The halide perovskite layer and precursors are drastically doping the PEDOT:PSS, its conductivity being increased by two orders of magnitude from 0.2 to 20 S cm−1. The depth of penetration of halide dopants is determined to be higher than 150 nm, superior to the usual thickness of PEDOT:PSS films. This phenomenon has important impact on diode leakage currents, on emission patterns of perovskite LEDs and on overestimated photocurrent density in perovskite solar cells embedding the PEDOT:PSS interlayer.  相似文献   

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