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Halogen Vacancies Enable Ligand‐Assisted Self‐Assembly of Perovskite Quantum Dots into Nanowires
摘要： Interest has been growing in defects of halide perovskites in view of their intimate connection with key material optoelectronic properties. In perovskite quantum dots (PQDs), the influence of defects is even more apparent than in their bulk counterparts. By combining experiment and theory, we report herein a halide-vacancy-driven, ligand-directed self-assembly process of CsPbBr3 PQDs. With the assistance of oleic acid and didodecyldimethylammonium sulfide, surface-Br-vacancy-rich CsPbBr3 PQDs self-assemble into nanowires (NWs) that are 20–60 nm in width and several millimeters in length. The NWs exhibit a sharp photoluminescence profile ( (cid:2) 18 nm full-width at-half-maximum) that peaks at 525 nm. Our findings provide insight into the defect-correlated dynamics of PQDs and defect-assisted fabrication of perovskite materials and devices.
关键词： self-assembly,perovskite quantum dot,halide vacancy,nanowire,CsPbBr3
更新于2025-09-19 17:13:59
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Enhancing effects of reduced graphene oxide on photoluminescence of CsPbBr <sub/>3</sub> perovskite quantum dots
摘要： The composites of CsPbBr3 perovskite quantum dots (PeQDs) and reduced graphene oxide (RGO) nanosheets have been synthesized by an in-situ solution reaction. The amount of RGO can significantly affect the photoluminescence of PeQDs. Varying with the amount of RGO, the photoluminescence quantum yield can be tuned from 48.4% to 69.3%. PL decay analysis indicates that the radiative decay rate and charge transfer become faster with increasing the amount of RGO. The ellipsomitric data can be described by a double Lorentz oscillator model. The comparison between bare and composite samples indicates that the complex refractive index can be affected by RGO composite. Numerical simulations on the electric field distribution for PeQD/RGO show that the local electric field around CsPbBr3 QDs is increased by surface plasmon resonance on the surface of RGO nanosheet. These results suggest that PeQD/RGO composite can be used for highly efficient light emitting devices.
关键词： FDTD,Surface plasmon resonance,Photoluminescence,Reduced graphene oxide,CsPbBr3 quantum dots
更新于2025-09-19 17:13:59
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All-Perovskite Photodetector with Fast Response
摘要： Perovskites have attracted substantial attention on account of their excellent physical properties and simple preparation process. Here we demonstrated an improved photodetector based on solution-processing organic-inorganic hybrid perovskite CH3NH3PbI3?xClx layer decorated with CsPbBr3 perovskite quantum dots. The CH3NH3PbI3?xClx-CsPbBr3 photodetector was operated in a visible light region, which appeared high responsivity (R = 0.39 A/W), detectivity (D* = 5.43 × 109 Jones), carrier mobility (μp = 172 cm2 V?1 s?1 and μn = 216 cm2 V?1 s?1), and fast response (rise time 121 μs and fall time 107 μs). The CH3NH3PbI3?xClx-CsPbBr3 heterostructure is anticipated to find comprehensive applications in future high-performance photoelectronic devices.
关键词： Perovskite,Fast response,CsPbBr3 quantum dots,Photodetector
更新于2025-09-19 17:13:59
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CsPbBr <sub/>3</sub> Quantum Dots as Artificial Antennas to Enhance the Light-Harvesting Efficiency and Photoresponse of Zinc Porphyrin
摘要： Broadening the spectral range and enhancing the efficiency of light-harvesting materials are important to the design of novel optoelectronic devices. In this work, CsPbBr3 quantum dots (QDs) are introduced as artificial antennas to enhance both the light-harvesting efficiency and photoresponse of zinc porphyrin (ZnP). The Fluorescence Resonance Energy Transfer (FRET) process both in solution and films from the donor CsPbBr3 QD to the acceptor ZnP have been systematically investigated, and an energy transfer efficiency over 70% in solution and a high optical sensitivity have been realized with the optimal of QD/ZnP ratio on films. A photocurrent density of up to 1.00×10-4 A·cm-2 can be achieved for the QD/ZnP film, and the corresponding on/off photocurrent value can be increased by two orders of magnitude compared with that of ZnP. Furthermore, the as-prepared light-harvesting film also demonstrates a high optical sensitivity at the optimal QD/ZnP ratio. Our research provides an effective way for designing and improving the QD/ZnP “antenna” for solar-energy harvesting devices.
关键词： Zinc Porphyrin,CsPbBr3 Quantum Dots,FRET,Photoresponse,Light-Harvesting Efficiency
更新于2025-09-19 17:13:59
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Highly Efficient CsPbBr3 Planar Perovskite Solar Cells via Additive Engineering with NH4SCN
摘要： Improving stability is a major aspect of the commercial application of perovskite solar cells (PSCs). The all inorganic CsPbBr3 perovskite material has been proven to have excellent stability. However, the CsPbBr3 film has a small range of light absorption and a serious charge recombination at the interface or inside the device, so that the power conversion efficiency is still lower than that of the organic-inorganic hybrid one. Here, we successfully fabricate high quality CsPbBr3 film via additive engineering with NH4SCN. By incorporating NH4+ and pseudo-halide ion SCN? into precursor solution, a smooth and dense CsPbBr3 film with good crystallinity and low trap state density can be obtained. At the same time, the results of a series of photoluminescence and electrochemical analyses including electrical impedance spectroscopy, space-charge limited current method, Mott-Schottky data, and so on, reveal that the NH4SCN additive can greatly reduce trap state density of the CsPbBr3 film, and also effectively inhibit interface recombination and promote charge transport in the CsPbBr3 planar PSC. Finally, the CsPbBr3 planar PSC prepared with molar ratio of 1.5 % NH4SCN achieves a champion efficiency of 8.47 %, higher than the pure one (7.12 %).
关键词： Additive engineer,Planar perovskite solar cells,CsPbBr3,Photovoltaic performance,NH4SCN
更新于2025-09-19 17:13:59
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p-GaN/n-ZnO Nanoplate/CsPbBr3 Quantum Dots Heterojunction Light-Emitting Diode for Dual-Wavelength Emission
摘要： In this paper, we report a p-GaN/n-ZnO nanoplate/CsPbBr3 quantum dots (QDs) heterojunction light-emitting diode (LED) for dual-wavelength emission. ZnO nanoplates were prepared by vapor phase transport on the GaN thin film to form the p-GaN/n-ZnO nanoplate heterojunction. Afterwards, green CsPbBr3 QDs (band gap of 2.25 eV) were deposited on ZnO nanoplates to realize green light emission. The structure and photoluminescence of the ZnO nanoplates and CsPbBr3 QDs were characterized. The as-prepared LED device with turn-on voltage of ~ 2.7 V displays a typical rectification behavior. The electroluminescence spectra with narrow emission peaks reveal the device presents commendable dual-wavelength electroluminescence performance at ~ 385 nm and ~ 512 nm and the electroluminescence intensity saturates at about 65 mA/cm2. Moreover, the detailed electroluminescence mechanism including emission originate of n-ZnO/p-GaN heterojunction was discussed based on the band diagram. Thus, our work indicates compelling potential for the practical application of perovskite LEDs.
关键词： CsPbBr3 QDs,Light emitting diode,electroluminescence,ZnO nanoplate
更新于2025-09-16 10:30:52
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The Scaling of Ligand Concentration and Soret Effect Induced Phase Transition in CsPbBr3 Perovskite Quantum Dots
摘要： The intelligent chemistry strategy based automated machine is applied for the study of the phase transition in the CsPbBr3 quantum dots (QDs). With the in-situ photoluminescence (PL) signal detector and analysis module, the oleyl amine (OLA) and oleyl acid (OA) ligands concentration dependent diffusion picture are well derived, a three-stage power-law scaling is disclosed on the ligands concentration dependent growth, and a phase transformation from CsPbBr3 to Cs4PbBr6 QDs are confirmed. Based on the experimental analysis associated with the G0W0-BSE calculation, we confirmed that there is no significant PL signal in the pure Cs4PbBr6 structure. With the steady temperature control module, we find the ligand concentration and the Soret effect are isomorphic for the mass flux in the QDs nucleation and phase transformation. We find the activity of the surface states can be essential for the size dependence of the Soret effect in a general way.
关键词： CsPbBr3,Soret effect,quantum dots,phase transition,ligand concentration
更新于2025-09-16 10:30:52
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Nucleation-controlled growth of superior long oriented CsPbBr <sub/>3</sub> microrod single crystals for high detectivity photodetectors
摘要： There has been great interest in the use of cesium lead bromide (CsPbBr3), which is one of the most important members of the all-inorganic perovskite family, due to its superior optoelectronic performance and higher stability. Recently, it has been demonstrated that it is advantageous to use CsPbBr3 microrods and nanowires in photodetectors because of their higher crystallinity, low amount of defects, and easy control of carrier transport along a specific direction as compared to their counterparts of single crystals and thin films. However, there is a shortage of adequate investigations that describe how to control the growth of CsPbBr3 microrods and nanowires so that they retain the optoelectronic performance of single CsPbBr3 microrods. Therefore, we are reporting how to control the growth of orientated dispersive super-long CsPbBr3 microrod single crystals (CsPbBr3 MSCs) via a simple anti-solvent method. The crucial factor in controlling the growth of dispersive super-long CsPbBr3 MSCs is the regulation of the rapid nucleation rate and slowing of the growth rate via controlling the di?usion velocity of anti-solvent methanol. We also reveal the growth mechanism of CsPbBr3 MSCs as layer-by-layer growth that originates from the 2D nucleus. The CsPbBr3 MSCs are revealed grew in the direction of [010], with the (101) facet exposed. Moreover, photodetectors based on one CsPbBr3 MSC were fabricated, and the detectivity (D) and the on/o? ratio were as high as 3.67 (cid:2) 1012 Jones and 988, respectively, suggesting a very strong optoelectronic response as photodetectors. The mechanism that the Cs ions and Cs vacancies use to move to negative and positive electrodes along the channels constructed by [PbBr6]4(cid:3) in the [010] direction of the CsPbBr3 MSC (101) facet was revealed, after activation by the applied electrical field, which is beneficial to enhance the optoelectronic response but does not reduce the device stability.
关键词： anti-solvent method,optoelectronic performance,microrod single crystals,photodetectors,CsPbBr3
更新于2025-09-16 10:30:52
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Cs <sub/>4</sub> PbBr <sub/>6</sub> /CsPbBr <sub/>3</sub> perovskite composites for WLEDs: pure white, high luminous efficiency and tunable color temperature
摘要： Cs4PbBr6/CsPbBr3 perovskite composites are fabricated by room-temperature one-pot mixing synthesis, which is short in time, free from inert gases and delivers a high product yield. Temperature-dependent photoluminescence shows that a larger exciton binding energy of 291.1 meV exhibits better thermal stability compared with that of pure Cs4PbBr6 and CsPbBr3 materials. The CIE chromaticity coordinates (0.1380, 0.7236) of green LEDs designed with Cs4PbBr6/CsPbBr3 perovskite composites show almost no variation under driving current changing from 5 to 30 mA. Furthermore, the ground Cs4PbBr6/CsPbBr3 perovskite composites mixed with red emitting K2SiF6:Mn4+ phosphor are dropped and casted on a blue-emitting InGaN chip. The white light emitting diodes (WLEDs) are presented, which have good luminous e?ciency of 65.33 lm W(cid:1)1 at 20 mA, a correlated color temperature of 5190 K, and the white gamut with chromaticity coordinate of (0.3392, 0.3336). According to the state of art, these excellent characteristics observed are much superior to the reported results of conventional perovskite-based WLEDs, which demonstrate the immense potential and great prospect of Cs4PbBr6/CsPbBr3 perovskite composites to replace conventional phosphors in lighting devices.
关键词： WLEDs,luminous efficiency,tunable color temperature,Cs4PbBr6/CsPbBr3 perovskite composites
更新于2025-09-16 10:30:52
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High-Intensity CsPbBr <sub/>3</sub> Perovskite LED using Poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) as Hole Transport and Electron-Blocking Layer
摘要： The majority of highly efficient perovskite light-emitting diodes (PeLED) contain PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrenesulfonate) as hole transport layer (HTL). However, the hygroscopic and acidic nature of PEDOT:PSS may lead to deterioration of PeLED performance. Moreover, due to its inferior electron-blocking properties, an additional electron-blocking layer (EBL) is required to establish charge balance and consequently obtain superior emission characteristics in typically electron-rich PeLED structures. In this work, PTAA (poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)) serving both as HTL and EBL is employed to substitute PEDOT:PSS in PeLED. The perovskite CsPbBr3 is chosen as emissive layer (EML) material due to its high color purity and photoluminescence (PL) quantum yield. Dense CsPbBr3 films are fabricated on PTAA-coated ITO substrates by employing a one-step spin-coating approach based on nonstoichiometric perovskite precursor solutions. To suppress non-radiative recombination, a small amount of methylammonium bromide (MABr) is incorporated in the CsPbBr3 lattice. The resulting films exhibit excellent coverage and PL intensity. PeLED containing pure CsPbBr3 films as EML show a green emission with a peak at 520 nm, maximum luminance of 11,000 cd/m2, an external quantum efficiency (EQE) of 3.3 % and a current efficiency (CE) of 10.3 cd/A. Further enhancement to 21,000 cd/m2, 7.5 % and 27.0 cd/A is demonstrated by PeLED with MABr-doped CsPbBr3 layers.
关键词： PTAA,perovskite light-emitting diodes,PEDOT:PSS,electron-blocking layer,CsPbBr3,hole transport layer
更新于2025-09-16 10:30:52