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1.
Yizhou Zhao Siyu Zhang Yue Lu Shangui Lan Cheng Zhu Jiawen Xiao Huachao Zai Manling Sui Dehui Li Huanping Zhou Yujing Li Qi Chen 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(6)
The low‐dimensional halide perovskites have received enormous attention due to their unique photovoltaic and optoelectronic performances. Periodic spacers are used to inhibit the growth of 3D perovskite and fabricate a 2D counterpart with layered structure, mostly based on organic/inorganic cations. Herein, by introducing organic anions (e.g., pentanedioic acid (PDA) and hexanedioic acid (HDA) simultaneously), leaf‐shaped (Cs3Pb2Br5)2(PDA–HDA) microplates with low‐dimensional structure are synthesized. They also exhibit significant photoluminescence (PL) centered at 540 nm with a narrow emission peak. The synthesis of single crystals of Pb(PDA) and Pb(HDA) allows to further clarify the crystal structure of (Cs3Pb2Br5)2(PDA–HDA) perovskite and its structural evolution mechanism. Moreover, the cooperative introduction of dicarboxylic acid pairs with appropriate lengths is thermodynamically favored for the low‐dimensional perovskite crystallization. The temperature‐dependent PL indicates a V‐shaped Stokes shift with elevated temperature that could be associated with the localization of excitons in the inorganic layers between organic dicarboxylic acid molecules. This work demonstrates low‐dimensional halide perovskite with anionic spacers, which also opens up a new approach to the growth of low‐dimensional organic–inorganic hybrid perovskite crystals. 相似文献
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En‐Ping Yao Zhanlue Yang Lei Meng Pengyu Sun Shiqi Dong Ye Yang Yang Yang 《Advanced materials (Deerfield Beach, Fla.)》2017,29(23)
Inorganic metal halide perovskite nanocrystals (NCs) have been employed universally in light‐emitting applications during the past two years. Here, blue‐emission (≈470 nm) Cs‐based perovskite NCs are derived by directly mixing synthesized bromide and chloride nanocrystals with a weight ratio of 2:1. High‐brightness blue perovskite light‐emitting diodes (PeLEDs) are obtained by controlling the grain size of the perovskite films. Moreover, a white PeLED is demonstrated for the first time by blending orange polymer materials with the blue perovskite nanocrystals as the active layer. Exciton transfer from the blue nanocrystals to the orange polymers via Förster or Dexter energy transfer is analyzed through time resolved photoluminescence. By tuning the ratio between the perovskite nanocrystals and polymers, pure white light is achieved with the a CIE coordinate at (0.33,0.34). 相似文献
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Seungjin Lee Da Bin Kim Jae Choul Yu Chung Hyeon Jang Jong Hyun Park Bo Ram Lee Myoung Hoon Song 《Advanced materials (Deerfield Beach, Fla.)》2019,31(20)
Metal halide perovskites (MHPs) have emerged as promising emitters because of their excellent optoelectronic properties, including high photoluminescence quantum yields (PLQYs), wide‐range color tunability, and high color purity. However, a fundamental limitation of MHPs is their low exciton binding energy, which results in a low radiative recombination rate and the dependence of PLQY on the excitation intensity. Under the operating conditions of light‐emitting diodes (LEDs), the injected current densities are typically lower than the trap density, leading to a low actual PLQY. Moreover, the defects not only initiate the decomposition of MHPs caused by extrinsic factors, but also intrinsically stimulate ion migration across the interface and lead to the corrosion of electrodes due to interaction between those electrodes, even under inert conditions. The passivation of defects has proven to be effective for mitigating the effects of defects in MHPs. Herein, the origins and theoretical calculations of the defect tolerance in MHPs and the impact of defects on both the performance and stability of perovskite LEDs are reviewed. The passivation methods and materials for MHP bulk films and nanocrystals are discussed in detail. Based on the currently reported advances, specific requirements and future research directions for display applications are suggested. 相似文献
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Li Na Quan Rafael Quintero‐Bermudez Oleksandr Voznyy Grant Walters Ankit Jain James Zhangming Fan Xueli Zheng Zhenyu Yang Edward H. Sargent 《Advanced materials (Deerfield Beach, Fla.)》2017,29(21)
Perovskite nanocrystals (NCs) have attracted attention due to their high photoluminescence quantum yield (PLQY) in solution; however, maintaining high emission efficiency in the solid state remains a challenge. This study presents a solution‐phase synthesis of efficient green‐emitting perovskite NCs (CsPbBr3) embedded in robust and air‐stable rhombic prism hexabromide (Cs4PbBr6) microcrystals, reaching a PLQY of 90%. Theoretical modeling and experimental characterization suggest that lattice matching between the NCs and the matrix contribute to improved passivation, while spatial confinement enhances the radiative rate of the NCs. In addition, dispersing the NCs in a matrix prevents agglomeration, which explains their high PLQY. 相似文献
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Fanghao Ye Huijun Zhang Wei Li Yu Yan Jinlong Cai Robert S. Gurney Andrew J. Pearson Dan Liu Tao Wang 《Small Methods》2019,3(3)
CsPbX3 perovskite nanocrystals (NCs) are promising light‐emitting materials that have gained significant attention over the past few years. The synthesis of CsPbX3 NCs is usually performed in an inert environment under high temperature conditions; however, this requirement hinders commercial development. Low‐temperature preparation of CsPbX3 NCs with rationally designed surface ligands is crucial to the performance and stability of CsPbX3 light‐emitting diodes (LEDs). In this work, short‐chain ligand‐anchored CsPbBr3 NCs in ambient conditions at room temperature are synthesized and a ligand‐exchange strategy is employed, using longer‐chain acid/amine ligand pairs, resulting in the dramatic improvement of performance and stability of CsPbBr3 NCs LEDs. It is found that CsPbBr3 NCs anchored by oleic acid and oleylamine complex ligands result in the best LED performance, with the maximum luminance of 5033 Cd m−2, current efficiency of 18.6 Cd A−1, external quantum efficiency of 5.4%, turn‐on voltage of 3.2 V, and the best thermal stability under ambient conditions. 相似文献
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Junqiang Li Sri Ganesh R. Bade Xin Shan Zhibin Yu 《Advanced materials (Deerfield Beach, Fla.)》2015,27(35):5196-5202
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Takuya Okamoto Vasudevanpillai Biju 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(32):2303496
Supramolecularly assembled high-order supercrystals (SCs) help control the dielectric, electronic, and excitonic properties of semiconductor nanocrystals (NCs) and quantum dots (QDs). Ligand-engineered perovskite NCs (PNCs) assemble into SCs showing shorter excitonic lifetimes than strongly dielectric PNC films showing long photoluminescence (PL) lifetimes and long-range carrier diffusion. Monodentate to bidentate ligand exchange on ≈ 8 nm halide perovskite (APbX3; A:Cs/MA, X:Br/I) PNCs generates mechanically stable SCs with close-packed lattices, overlapping electronic wave functions, and higher dielectric constant, providing distinct excitonic properties from single PNCs or PNC films. From Fast Fourier Transform (FFT) images, time-resolved PL, and small-angle X-ray scattering, structurally and excitonically ordered large SCs are identified. An Sc shows a smaller spectral shift (<35 meV) than a PNC film (>100 meV), a microcrystal (>100 meV), or a bulk crystal (>100 meV). Also, the exciton lifetime (<10 ns) of an SC is excitation power-independent in the single exciton regime 〈N〉<1, comparable to an isolated PNC. Therefore, bidentate-ligand-assisted SCs help overcome delayed exciton or carrier recombination in halide perovskite nanocrystal assemblies or films. 相似文献
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Ying‐Chieh Wong Wen‐Bin Wu Tian Wang Jun De Andrew Ng Khoong Hong Khoo Jie Wu Zhi‐Kuang Tan 《Advanced materials (Deerfield Beach, Fla.)》2019,31(24)
Lead halide perovskite possesses a semiconductor bandgap that is readily tunable by a variation in its halide composition. Here, a photo‐activated halide exchange process between perovskite nanocrystals and molecular haloalkanes is reported, which enables the perovskite luminescence to be controllably shifted across the entire visible spectrum. Mechanistic investigations reveal a mutual exchange of halogens between the perovskite crystal surface and a chemisorbed haloalkane, yielding nanocrystals and haloalkanes with mixed halide contents. Exchange kinetics studies involving primary, secondary, and tertiary haloalkanes show that the rate of reaction is governed by the activation barrier in the breakage of the covalent carbon–halogen (C? X) bond, which is a function of the C? X bond energy and carbon radical stability. Employing this halide exchange approach, a micrometer‐scale trichromatic patterning of perovskites is demonstrated using a light‐source‐integrated inkjet printer and tertiary haloalkanes as color‐conversion inks. The haloalkanes volatilize after halide exchange and leave no residues, thereby offering significant processing advantage over conventional salt‐based exchange techniques. Beyond the possible applications in new‐generation micro‐LED and electroluminescent quantum dot displays, this work exemplifies the rich surface and photochemistry of perovskite nanocrystals, and could lead to further opportunities in perovskite‐based photocatalysis and photochemical sensing. 相似文献
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Hong‐Hua Fang Loredana Protesescu Daniel M. Balazs Sampson Adjokatse Maksym V. Kovalenko Maria Antonietta Loi 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(32)
The optical properties of the newly developed near‐infrared emitting formamidinium lead triiodide (FAPbI3) nanocrystals (NCs) and their polycrystalline thin film counterpart are comparatively investigated by means of steady‐state and time‐resolved photoluminescence. The excitonic emission is dominant in NC ensemble because of the localization of electron–hole pairs. A promisingly high quantum yield above 70%, and a large absorption cross‐section (5.2 × 10?13 cm?2) are measured. At high pump fluence, biexcitonic recombination is observed, featuring a slow recombination lifetime of 0.4 ns. In polycrystalline thin films, the quantum efficiency is limited by nonradiative trap‐assisted recombination that turns to bimolecular at high pump fluences. From the temperature‐dependent photoluminescence (PL) spectra, a phase transition is clearly observed in both NC ensemble and polycrystalline thin film. It is interesting to note that NC ensemble shows PL temperature antiquenching, in contrast to the strong PL quenching displayed by polycrystalline thin films. This difference is explained in terms of thermal activation of trapped carriers at the nanocrystal's surface, as opposed to the exciton thermal dissociation and trap‐mediated recombination, which occur in thin films at higher temperatures. 相似文献
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Shuai Gu Renxing Lin Qiaolei Han Yuan Gao Hairen Tan Jia Zhu 《Advanced materials (Deerfield Beach, Fla.)》2020,32(27):1907392
Metal halide perovskites have recently attracted enormous attention for photovoltaic applications due to their superior optical and electrical properties. Lead (Pb) halide perovskites stand out among this material series, with a power conversion efficiency (PCE) over 25%. According to the Shockley–Queisser (SQ) limit, lead halide perovskites typically exhibit bandgaps that are not within the optimal range for single-junction solar cells. Partial or complete replacement of lead with tin (Sn) is gaining increasing research interest, due to the promise of further narrowing the bandgaps. This enables ideal solar utilization for single-junction solar cells as well as the construction of all-perovskite tandem solar cells. In addition, the usage of Sn provides a path to the fabrication of lead-free or Pb-reduced perovskite solar cells (PSCs). Recent progress in addressing the challenges of fabricating efficient Sn halide and mixed lead–tin (Pb–Sn) halide PSCs is summarized herein. Mixed Pb–Sn halide perovskites hold promise not only for higher efficiency and more stable single-junction solar cells but also for efficient all-perovskite monolithic tandem solar cells. 相似文献
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Yen‐Hung Lin Pichaya Pattanasattayavong Thomas D. Anthopoulos 《Advanced materials (Deerfield Beach, Fla.)》2017,29(46)
Following the unprecedented rise in photovoltaic power conversion efficiencies during the past five years, metal‐halide perovskites (MHPs) have emerged as a new and highly promising class of solar‐energy materials. Their extraordinary electrical and optical properties combined with the abundance of the raw materials, the simplicity of synthetic routes, and processing versatility make MHPs ideal for cost‐efficient, large‐volume manufacturing of a plethora of optoelectronic devices that span far beyond photovoltaics. Herein looks beyond current applications in the field of energy, to the area of large‐area electronics using MHPs as the semiconductor material. A comprehensive overview of the relevant fundamental material properties of MHPs, including crystal structure, electronic states, and charge transport, is provided first. Thereafter, recent demonstrations of MHP‐based thin‐film transistors and their application in logic circuits, as well as bi‐functional devices such as light‐sensing and light‐emitting transistors, are discussed. Finally, the challenges and opportunities in the area of MHPs‐based electronics, with particular emphasis on manufacturing, stability, and health and environmental concerns, are highlighted. 相似文献
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Junwei Xu Wenxiao Huang Peiyun Li Drew R. Onken Chaochao Dun Yang Guo Kamil B. Ucer Chang Lu Hongzhi Wang Scott M. Geyer Richard T. Williams David L. Carroll 《Advanced materials (Deerfield Beach, Fla.)》2017,29(43)
Solution‐grown films of CsPbBr3 nanocrystals imbedded in Cs4PbBr6 are incorporated as the recombination layer in light‐emitting diode (LED) structures. The kinetics at high carrier density of pure (extended) CsPbBr3 and the nanoinclusion composite are measured and analyzed, indicating second‐order kinetics in extended and mainly first‐order kinetics in the confined CsPbBr3, respectively. Analysis of absorption strength of this all‐perovskite, all‐inorganic imbedded nanocrystal composite relative to pure CsPbBr3 indicates enhanced oscillator strength consistent with earlier published attribution of the sub‐nanosecond exciton radiative lifetime in nanoprecipitates of CsPbBr3 in melt‐grown CsBr host crystals and CsPbBr3 evaporated films. 相似文献
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Halide perovskites have high light absorption coefficients, long charge carrier diffusion lengths, intense photoluminescence, and slow rates of non‐radiative charge recombination. Thus, they are attractive photoactive materials for developing high‐performance optoelectronic devices. These devices are also cheap and easy to be fabricated. To realize the optimal performances of halide perovskite‐based optoelectronic devices (HPODs), perovskite photoactive layers should work effectively with other functional materials such as electrodes, interfacial layers and encapsulating films. Conventional two‐dimensional (2D) materials are promising candidates for this purpose because of their unique structures and/or interesting optoelectronic properties. Here, we comprehensively summarize the recent advancements in the applications of conventional 2D materials for halide perovskite‐based photodetectors, solar cells and light‐emitting diodes. The examples of these 2D materials are graphene and its derivatives, mono‐ and few‐layer transition metal dichalcogenides (TMDs), graphdiyne and metal nanosheets, etc. The research related to 2D nanostructured perovskites and 2D Ruddlesden–Popper perovskites as efficient and stable photoactive layers is also outlined. The syntheses, functions and working mechanisms of relevant 2D materials are introduced, and the challenges to achieving practical applications of HPODs using 2D materials are also discussed. 相似文献
17.
Shaomin Peng Sisi Wang Dandan Zhao Xiaojun Li Chao Liang Junmin Xia Tianqi Zhang Guichuan Xing Zikang Tang 《Small Methods》2019,3(10)
Metal halide perovskites witness a huge development in light‐emitting diodes (LEDs) triggered by their unique optical and optoelectronic properties. However, blue emission perovskite LEDs lag behind their red and green counterparts in efficiency, due to the difficulties in synthesizing stable materials and maintaining quantum efficiency in thin films as high as in solution. The nanoplatelets (NPLs), with exciton binding energies up to several hundreds of meV, exhibit fundamentally different excitonic behavior from 0D nanocrystals. Meanwhile the bandgap tunability with thickness makes them promising for blue optoelectronic devices. Here, a brief review on recent progress in perovskite light emission, and the opportunities and challenges in pure bromide‐based perovskite NPLs for the blue‐emitting regime are provided. In particular, the important roles of surface ligands and emitting layer quality on devices are highlighted. The trade‐off between well surface passivation and efficient charge transportation is analyzed. Furthermore, it is recommended that more efforts should be put on exploring the carrier dynamics in NPLs, which act as guidelines for optimization of materials and improvement of devices. 相似文献
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《Small Methods》2018,2(3)
In recent years, halide perovskites have been attracting intense attention as novel materials for photovoltaic applications due to their high carrier mobility, extraordinarily long carrier diffusion lengths, and suitable optical bandgaps. Furthermore, there are extensive applications of halide perovskites owing to their exceptional attributes in different areas, such as light‐emitting diodes, lasers, X‐ray detectors, memory devices, and more. Here, the unique characteristics of halide perovskite materials are described, including their electrical and optical properties, to explain why these materials are so exciting for a wide variety of applications. After introducing the synthesis techniques used to prepare halide perovskite films, recent advances on the applications of halide perovskites beyond photovoltaics are addressed. The challenges to be overcome for several applications are described and it is suggested that halide perovskites are equivalent to a gold standard in developing next‐generation optoelectronic and electronic devices. 相似文献
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Fuzhi Wang Zhenye Wang Wenda Sun Zhibin Wang Yiming Bai Tasawar Hayat Ahmed Alsaedi Zhan&#x;ao Tan 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(32)
For quasi‐2D perovskite light‐emitting diodes, the introduction of insulating bulky cation reduces the charge transport property, leading to lowered brightness and increased turn‐on voltage. Herein, a dual‐ligand strategy is adopted to prepare perovskite films by using an appropriate ratio of i‐butylammonium (iBA) and phenylethylammonium (PEA) as capping ligands. The introduction of iBA enhances the binding energy of the ligands on the surface of the quasi‐2D perovskite, and effectively controls the proportion of 2D perovskite to allow more efficient energy transfer, resulting in the great enhancement of the electric and luminescent properties of the perovskite. The photoluminescence (PL) mapping of the perovskite films exhibits that enhanced photoluminescence performance with better uniformity and stronger intensity can be achieved with this dual‐ligand strategy. By adjusting the proportion of the two ligands, sky‐blue perovskite light‐emitting diodes (PeLEDs) with electroluminescence (EL) peak located 485 nm are achieved with a maximum luminance up to 1130 cd m?2 and a maximum external quantum efficiency (EQE) up to 7.84%. In addition, the color stability and device stability are significantly enhanced by using a dual‐ligand strategy. This simple and feasible method paves the way for improving the performance of quasi‐2D PeLEDs. 相似文献
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Natalia Yantara Annalisa Bruno Azhar Iqbal Nur Fadilah Jamaludin Cesare Soci Subodh Mhaisalkar Nripan Mathews 《Advanced materials (Deerfield Beach, Fla.)》2018,30(33)
Mixed Ruddlesden–Popper (RP) perovskites are of great interest in light‐emitting diodes (LEDs), due to the efficient energy transfer (funneling) from high‐bandgap (donor) domains to low‐bandgap (acceptor) domains, which leads to enhanced photoluminescence (PL) intensity, long PL lifetime, and high‐efficiency LEDs. However, the influence of reduced effective emitter centers in the active emissive film, as well as the implications of electrical injection into the larger bandgap donor material, have not been addressed in the context of an active device. The electrical and optical signatures of the energy cascading mechanisms are critically assessed and modulated in a model RP perovskite series ((C8H17NH3)2(CH(NH2)2)m?1PbmBr3m+1). Optimized devices demonstrate a current efficiency of 22.9 cd A?1 and 5% external quantum efficiency, more than five times higher than systems where funneling is absent. The signature of nonideal funneling in RP perovskites is revealed by the appearance of donor electroluminescence from the device, followed by a reduction in the LED performance 相似文献