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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - A Synthetic Method for Extremely Stable Thin Film of CsPbBr<inf>3</inf> QDs and its Application on Light-emitting Diodes
摘要： The ability to be mixed with the polymers is very important for applications of perovskite quantum dots (QDs), such as in display, lighting and so on. Here, a method for fabricating a thin film composed of CsPbBr3 QDs and polydimethylsiloxane (PDMS) was reported. By using the ethyl acetate, a large number of ligands on the surface were removed and the combination with polymers can realize. Based on the thin film, an LED device was assembled and its luminous flux, luminous efficiency, color temperature and CIE color coordinates were measured. What’s more, the thin film revealed a splendid stability after being stored for 42 days without any protection, which show the broad prospects of it.
关键词： Inorganic perovskite quantum dots,Stability,Light-emitting diodes
更新于2025-11-19 16:46:39
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Investigation of sol-gel and nanoparticle-based NiOx hole transporting layer for high-performance planar perovskite solar cells
摘要： We conduct a comprehensive study on and comparison of sol-gel and nanoparticles (NPs)-based nickel oxide hole-transporting layer (HTL) for high-performance planar perovskite solar cells (PSCs). The characteristics and film properties of sol-gel and NPs were systemically investigated using ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and photoluminescence (PL), and its effect on device-performance was also examined using J-V characteristics, quantum-efficiency, and the VOC dependence of the light intensity. Through this comparison of two types of HTL and their device-performances, these studies can provide sufficient and robust information for nickel oxide-based PSCs, and furthermore, the overall results and discussions can be useful for high-performance PSCs.
关键词： Nickel oxide,Planar perovskite solar cells,Hole transporting layer,Sol-gel,Nanoparticles
更新于2025-11-19 16:46:39
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Reorientational dynamics of organic cations in perovskite-like coordination polymers
摘要： Here we report the dynamics of organic cations as guest molecules in a perovskite host-framework. The molecular motion of CH3NH3+ (MAFe), (CH3)2NH2+ (DMAFe) and (CH3)3NH+ (TrMAFe) in the cage formed by KFe(CN)63? units was studied using a combination of experimental methods: (i) thermal analysis, (ii) dielectric and electric studies, (iii) optical observations, (iv) EPR and 1H NMR spectroscopy and (v) quasielastic neutron scattering (QENS). In the case of MAFe and TrMAFe, the thermal analysis reveals one solid-to-solid phase transition (PT) and two PTs for the DMAFe crystal. A markedly temperature-dependent dielectric constant indicates the tunable and switchable properties of the complexes. Also, their semiconducting properties are confirmed by a dc conductivity measurement. The broadband dielectric relaxation is analyzed for the TrMAFe sample in the frequency range of 100 Hz–1 GHz. QENS shows that we deal rather with the localized motion of the cation than a diffusive one. Three models, which concern the simultaneous rotation of the CH3 and/or NH3 group, π-flips and free rotations of the organic cation, are used to fit the elastic incoherent structure factor. The 1H NMR spin–lattice relaxation time for all compounds under study, as well as the second moments, has been measured in a wide temperature range. In all studied samples, the temperature dependence of the second moment of the proton NMR line indicated the gradual evolution of the molecular movements from the rigid state up to a highly disordered one.
关键词： quasielastic neutron scattering,phase transitions,perovskite,coordination polymers,dielectric properties,NMR spectroscopy,dynamics,organic cations
更新于2025-11-14 17:28:48
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Stable, Color-Tunable 2D SCN-Based Perovskites: Revealing the Critical Influence of Asymmetric Pseudo-Halide on Constituent Ions
摘要： Two-dimensional (2D) layered perovskites (An+1BnX3n+1, n = 1, 2, …) have lately attracted significant research interest because of their enhanced ambient stability comparing to the conventional 3D counterparts. Beside the common A-site cation engineering, using an asymmetric pseudo-halide, SCN, anion in X-site anion has been recently proven as another effective approach to constitute 2D perovskite. Among them, 2D (MA)2Pb(SCN)2I2 was most widely investigated and honored as a promising material owing to its decent optoelectronic properties; however, its poor stability arouses concerns from the recent researches. In this study, a systematical composition engineering of A2Pb(SCN)2X2 (A= FA+, MA+, Cs+ and X= Br-, I-) was conducted. Our results revealed that linear SCN- anion may dictate critical restrictions on the constituent ions of its derived 2D framework (PbX4(SCN)2), which has not been extensively discussed yet. We demonstrated that using a smaller Cs+ cation can afford a more favorable 2D structure compared with the MA+ cation. Cs2Pb(SCN)2I2 was revealed to possess improved stability and photo-response compared to (MA)2Pb(SCN)2I2. Interestingly, Cs2Pb(SCN)2I2 and (MA)2Pb(SCN)2I2 seem to possess distinct electronic band structures as indicated by their discrepant photoluminescence spectra, for which the former exhibits a rather intense singlet emission at room temperature, as opposed to the latter having a dominant emission associated with triplet or defective states. Furthermore, using a smaller Cs+ cation also enables facile replacement of smaller halide anion. A series of mix-halide 2D Cs2Pb(SCN)2(I1-xBrx)2 (x = 0, 1/3, 1/2, 2/3, 1) with variant vivid color was explored by both calculation and experimental efforts to corroborate the further enhanced stability when x value increases. The results revealed in this work might be inherent trait of 2D SCN-based perovskites and also unveil that all inorganic 2D Cs2Pb(SCN)2X2 perovskite system is a promising class of material with decent stability and color-tunability, deserving further explorations.
关键词： stability,Cs cation,pseudo-halide,SCN- anion,color-tunability,2D perovskite
更新于2025-11-14 17:04:02
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Improved photovoltaic performance of perovskite solar cells by utilizing down-conversion NaYF <sub/>4</sub> :Eu <sup>3+</sup> nanophosphors
摘要： Perovskite solar cells assembled with titanium dioxide electron transport layer exhibited brilliant photovoltaic properties due to titanium dioxide having a high electron mobility, appropriate energy level alignment and easy fabrication procedure. However, inherent instability exists in titanium dioxide-based perovskite solar cells because of the ultraviolet photocatalytic activity of titanium dioxide. This results in recombination at the interface of titanium dioxide/perovskite. In this report, the down-conversion nanocrystals film made of europium-doped sodium yttrium fluoride was deposited on the non-conducting side of the conducting glass. The down-conversion nanocrystal layer could absorb high energy ultraviolet photons and converted them to visible light. The layer not only extended the spectral response range for perovskite solar cells but also alleviated the photocatalytic activity of titanium dioxide. The perovskite solar cells with the down-conversion nanocrystals film generated average power conversion efficiency yield of 19.99%, which is much better than that of the device without the down-conversion nanocrystals film (16.99%). The best power conversion efficiency for the device with the down-conversion nanocrystals film was 20.17%. In addition, perovskite solar cells with the down-conversion nanocrystals film showed a small hysteresis.
关键词： titanium dioxide,down-conversion,NaYF4:Eu3+ nanophosphors,photovoltaic performance,perovskite solar cells
更新于2025-11-14 17:04:02
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Short-chain ligand assisted synthesis of CH3NH3PbX3 (X = Cl, Br, I) perovskite quantum dots and improved morphology of CH3NH3PbBr3 thin films
摘要： Employing the short-chain C4H9NH3X (X = Cl, Br, I) compound as the unique capping agent, highly quality CH3NH3PbX3 (X = Cl, Br, I) perovskite quantum dots can be synthesized at room temperature in the open air, which possess high photoluminescence quantum yields and tunable emission in the range of 440-660 nm. Besides, C4H9NH3Br can also improve the morphology of CH3NH3PbBr3 thin films by spin-coating the N, N-dimerthylformamide solution of CH3NH3Br, C4H9NH3Br and PbBr2, making the thin film dense and compact, and improving its optical properties.
关键词： quantum dots,Perovskite,CH3NH3PbX3(Cl, Br, I),photoluminescence spectra,morphology
更新于2025-11-14 17:04:02
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Electron Transport Improvement of Perovskite Solar Cell via ZIF-8 Derived Porous Carbon Skeleton
摘要： To improve electron transport rate of perovskite solar cell, ZIF-8 derived porous carbon skeleton layer is prepared by carbonizing the ZIF-8 thin film on conducting glass as the electron transport skeleton of perovskite solar cell. Polyvinyl pyrrolidone is added during the synthesis of ZIF-8 to reduce the particle size of ZIF-8 and decrease the carbonization temperature below 600°C. The porous structure of ZIF-8 is mainly reserved at the optimized carbonization temperature. Then TiO2 nanoparticles are deposited on the surface of porous carbon skeleton to form an electron transport layer of perovskite solar cell with the structure of FTO/ZIF-8 derived porous carbon layer/TiO2/Perovskite/Spiro-OMeTAD/Au. Due to the good conductivity of the ZIF-8 derived porous carbon skeleton, the photogenerated electron transport rate of perovskite solar cell is increased. At the same time, the porous structure of ZIF-8 derived carbon layer increases the contact area between the perovskite layer and the TiO2 layer to favor separation of photogenerated charges. Therefore, the light-to-electric conversion efficiency of CH3NH3PbI3 perovskite solar cell is enhanced from 14.25% to 17.32%.
关键词： Electron transport,Increase of contact area,Porous carbon skeleton,Good conductivity,Polyvinyl pyrrolidone,Perovskite solar cell,Metal organic frameworks
更新于2025-11-14 17:04:02
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Ligand Engineering for Improved All‐Inorganic Perovskite Quantum Dot‐MoS <sub/>2</sub> Monolayer Mixed Dimensional van der Waals Phototransistor
摘要： Combining intriguing physical properties of 2D crystals and intrinsically remarkable optical properties of halide perovskite quantum dots (QDs), the 0D–2D perovskite QD–based mixed dimensional van der Waals heterostructure (MvdWH) is considered as promising for optoelectronic applications. Even though the interfacial electronic structure of MvdWHs is sufficiently engineered to manipulate the charge carrier behavior, the issue of interfacial charge transfer efficiency originating from the residue ligands that are inevitably introduced by the QDs is still prominently remained. From this perspective, for the first time, a solution-processed surface ligand density control strategy is demonstrated to balance the QD surface passivation and the interfacial charge carrier extraction and injection efficiency in the 0D–2D MvdWH system. The accurate adjustment of ligand density outside QDs enables the subsequent modulation on interfacial charge carrier transfer efficiency from the aspect of electronic and optoelectronic properties. Furthermore, such kind of ligand engineering toward MvdWH interface is substantially demonstrated in a photogating mechanism–based phototransistor with an improved photoresponsivity as high as 1.13 × 105 A W?1. These results may push forward the evolution of 0D–2D mixed dimensional van der Waals optoelectronics.
关键词： mixed-dimensional van der Waals heterostructures,perovskite quantum dots,phototransistors,MoS2,ligand engineering
更新于2025-11-14 17:04:02
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Preparation of high quality perovskite thin film in ambient air using ethylacetate as anti-solvent
摘要： Methylamine lead iodide (CH3NH3PbI3) perovskite thin film solar cell has attracted much attention due to its low cost and high photoelectric conversion efficiency. Preparation of high quality perovskite thin film is the key to obtain high conversion efficiency of solar cells. Here, the pinhole-free CH3NH3PbI3 layer with high coverage and smooth surface is prepared by the one-step solution method in air with ethylacetate as anti-solvent on an electron transport hybrid layer of TiO2 nanoparticles coated porous carbon. The effect of ethylacetate as anti-solvent on the quality of perovskite thin film is studied in detail by comparing with chlorobenzene and ethylether. The high saturation and humidity resistance of ethylacetate in air control the nucleation and growing kinetics of perovskite crystals during the spin coating process, which facilitates the formation of uniform pinhole-free perovskite thin films. The perovskite solar cell based on the prepared high quality thin film achieves the highest conversion efficiency of 17.41% in ambient air with a relative humidity of 35%, which is superior to the perovskite thin films prepared with chlorobenzene and ethylether (conversion efficiency of 10.80% and 10.20%). The higher light-to-electric conversion efficiency is due to high coverage of the pinhole-free perovskite thin film and good contact with the electron transport layer and the hole transport layer.
关键词： Anti-solvent,Perovskite solar cell,Uniform perovskite thin film,Ethylacetate
更新于2025-11-14 17:03:37
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All-inorganic RbxCs1-xPbBrI2 perovskite nanocrystals with wavelength-tunable properties for red light-emitting
摘要： The outstanding photovoltaic performance of perovskite nanocrystals is attracting more and more attention. However, how to obtain stable wavelength-tunable red light-emitting perovskite materials is an urgent problem to be solved for the photovoltaic application. This paper reports a kind of orange to red light-emitting rubidium?cesium lead halide perovskite nanocrystals (RbxCs1-xPbBrI2, x = 0 to x = 0.6). By adjusting the rubidium?cesium ratios in the precursor solution, the peak wavelength can be tuned from 631 nm to 588 nm. The nanocrystals have narrow emission line-widths and bright photoluminescence. Furthermore, the polymer nanocrystals are prepared simply by mixing PMMA and perovskite nanocrystals solution in appropriate ratios, forming a series of stable orange to red emitting materials.
关键词： Nanocrystals,Rubidium,Stability,Photoluminescence,Perovskite
更新于2025-11-14 17:03:37