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MAPbI3 nanowires prepared by a facile Vapor Transfer Method for simple photodetector
摘要： MAPbI3 nanowires have become one of the promising materials for optoelectronic devices. Herein, a simple template-free vapor transfer approach to synthesize MAPbI3 nanowires on various substrates for optoelectronic device developed. High crystalline MAPbI3 nanowires were realized via methyl-ammonium iodide (MAI) vapor transfer treatment with PbI2 nanowires. PbI2 nanowires were prepared by a self-assembled procedure where PbI2 film was recrystallized and converted to nanowires structure with the exposure of dimethylacetamide (DMAC) vapor. On top of that, the density of MAPbI3 nanowires could be modulated by simply tuning the thickness of PbI2 film. The as-fabricated MAPbI3 nanowires photodetector exhibits a satisfying responsivity of 0.115 A W-1 @3V while the rise time is less than 0.63 s and the decay time is less than 0.73 s. The study presents a bright future of MAPbI3 nanowires for optoelectronic application.
关键词： vapor transfer method,organic mixed halide perovskite,nanowires,nanocrystalline materials,photodetector,sensors
更新于2025-09-11 14:15:04
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Surface Modification for Improving the Photocatalytic Polymerization of 3,4-Ethylenedioxythiophene over Inorganic Lead Halide Perovskite Quantum Dots
摘要： Inorganic lead halide perovskite quantum dots (iLHP-QDs) have recently been used in the photocatalytic reaction. However, the factors that influence the photocatalytic performance of the iLHP-QDs has not been fully investigated. Herein, we synthesised a series of iLHP-QDs with varied halide ratio (CsPbX3, X=I, I0.67Br0.33, I0.5Br0.5, I0.33Br0.67, Br) and studied its influence on the photocatalytic performance by monitoring the polymerization of TerEDOT. The CsPbI3 QDs showed the best performance owing to its narrow bandgap and low exciton binding energy. Moreover, the photocatalytic performance of the iLHP-QDs could be simply improved by being treated with methyl acetate, which can be attributed to the replacement of the oleic acid by the short acetate acid, and the introduction of the traps on the surface of QDs in the post-treatment. These results could help design more efficient photocatalytic system and further promote the application of iLHP-QDs.
关键词： photocatalytic performance,quantum dots,exciton binding energy,charge transport efficiency,halide perovskite
更新于2025-09-11 14:15:04
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Insights into Fullerene Passivation of SnO <sub/>2</sub> Electron Transport Layers in Perovskite Solar Cells
摘要： 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.
关键词： solar cell,fullerene,metal halide perovskite,tin oxide,passivation
更新于2025-09-11 14:15:04
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CH3NH3PbBr3 Nanocrystals Formed in situ in Polystyrene Used for Increasing the Color Rendering Index of White Leds
摘要： A new method is proposed for the formation of MAPbBr3 nanoparticles in situ in a dispersion of polystyrene in toluene in the absence (MAPbBr3@PS) and presence of a broad-band luminophor (MAPbBr3/GAG:Ce@PS). This method permits the lossless use of perovskite, a uniform distribution of the luminophor nanoparticles in the polymer matrix, and maintenance of a high photoluminescence quantum yield (~46%). The samples derived from MAPbBr3 have green photoluminescence with a maximum showing a blue shift in going from bulk perovskite powder to films due to a size effect. The use of nanocomposite films MAPbBr3/GAG:Ce@PS in white LEDs permits enhancement of the color rendering index to 92 with correlation color temperature >5800 K.
关键词： nanocomposite films,quantum yield,photoluminescence,hybrid halide perovskite
更新于2025-09-11 14:15:04
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Design principle of all-inorganic halide perovskite-related nanocrystals
摘要： All-inorganic halide perovskite (AIHP)-related (e.g., CsPbBr3, Cs4PbBr6, and CsPb2Br5) nanocrystals have attracted great research interest in the recent three years, owing to their unique optical properties. However, rational structural and compositional control of these nanocrystals is still challenging, particularly using the room temperature saturated recrystallization (RTSR) method. Here, we revealed that the structure and the composition of the nanocrystals fabricated by the RTSR approach are highly dependent not only on the previously thought concentration ratio of PbBr2 and CsBr in N-dimethylformamide (DMF), but the previously neglected absolute concentration and reaction time. This is the reason why pure AIHP-related nanocrystals are usually difficult to prepare using the RTSR method. Through a series of carefully designed experiments, we obtained the evolution trend of the precipitation rate of PbBr2 and CsBr within a wide concentration range in DMF. Based on the understanding of the growth mechanism, we achieved preparation of pure or a mixture of CsPbBr3, Cs4PbBr6, and CsPb2Br5 nanocrystals through either control of the concentration of PbBr2 and CsBr or the reaction time. This study deepens our understanding of the growth mechanism of AIHP-related nanocrystals, paving the way for future engineering of nanocrystals with desired structures and compositions. These structures with desired compositions will definitely have promising applications in optical and optoelectronic devices.
关键词： nanocrystals,All-inorganic halide perovskite,room temperature saturated recrystallization,optical properties,optoelectronic devices
更新于2025-09-10 09:29:36
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Scalable Graphene-on-Organometal Halide Perovskite Heterostructure Fabricated by Dry Transfer
摘要： Graphene, a single layer conductor, can be combined with other functional materials for building efficient optoelectronic devices. However, transferring large-area graphene onto another material often involves dipping the material into water and other solvents. This process is incompatible with water-sensitive materials such as organometal halide perovskites. Here, a dry method is used and succeeded, for the first time, in stacking centimeter-sized graphene directly onto methylammonium lead iodide thin films without exposing the perovskite film to any liquid. Photoemission spectroscopy and nanosecond time-resolved photoelectrical measurement show that the graphene/perovskite interface does not contain significant amount of contaminants and sustain efficient interfacial electron transfer. The use of this method in fabricating graphene-on-perovskite photodetectors is further demonstrated. Besides a better photoresponsivity compared to detectors fabricated by the conventional perovskite-on-graphene structure, this dry transfer method provides a scalable pathway to incorporate graphene in multilayer devices based on water-sensitive materials.
关键词： photodetectors,interfaces,organometal halide perovskite,graphene,charge transfer
更新于2025-09-10 09:29:36
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Room-temperature synthesis of Mn2+-doped cesium lead halide perovskite nanocrystals via a transformation doping method
摘要： Currently, Mn2+-doped cesium lead halide perovskite nanocrystals have attracted research interests. Here, we report a novel room-temperature transformation doping method for the synthesis of Mn2+-doped CsPbCl3 and CsPb(Br/Cl)3 nanocrystals. Innovatively, the transformation of Cs4PbX6 (X=Cl, Br) phase which has no excitation emission to CsPbX3 phase which has strong luminescence was used in this mechanism. Simply injecting MnCl2 precursor into Cs4PbX6 solution could result in the full transformation of Cs4PbX6 phase to CsPbX3 phase and Mn2+-doped CsPbCl3 or CsPb(Br/Cl)3 were obtained. The basic idea for the transformation doping method is that MnCl2 can not only drive the transformation of the two structures but also Mn2+ can substitute Pb2+. In this reaction, the concentration of Mn precursor is a key influence factor. Moreover, instead of the ligand of OA, the acetic acid was used in our method. Through the adjustment of the ligand in precursor, not just the photoluminescence quantum yields of as-prepared Mn2+-doped CsPbCl3 nanocrystals were improved from 7.8 to 32.6% (Mn2+-doped CsPb(Br/Cl)3 nanocrystals even could reach to 42.7%), the nanocrystals also retained outstanding stability. We propose a combination of structure transformation and ion doping as a perovskite doping mechanism. Our doping method is a novel strategy for lead halide perovskite nanocrystals doping project and it could provide more possibilities in the future.
关键词： photoluminescence quantum yields,Cs4PbX6,Mn2+-doped cesium lead halide perovskite nanocrystals,CsPbX3,room-temperature transformation doping method
更新于2025-09-09 09:28:46
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Phase Intergrowth and Structural Defects in Organic Metal Halide Ruddlesden–Popper Thin Films
摘要： Organic metal halide Ruddlesden?Popper layered perovskite phases combine the excellent optoelectronic properties of three-dimensional, bulk hybrid perovskites with superior material stability under ambient conditions. However, the thin film structure of these layered perovskites is still poorly understood, as phase purity is typically determined solely by specular X-ray diffraction. The thin film structure of these Ruddlesden?Popper phases was examined by increasingly local characterization techniques. From the comparison of grazing-incidence wide-angle X-ray scattering patterns of cast films to expected scattering from single-crystal structures, significant in-plane disorder was observed. Spatially localized photoluminescence measurements show that films do not phase separate on the micrometer scale. Selected area electron diffraction measurements show the intergrowth of different phases within the same thin film, consistent with previous observations seen in epitaxially grown Ruddlesden?Popper complex oxides. Despite the presence of phase impurities that would typically be detrimental for device performance, fits to photothermal deflection spectroscopy measurements show relatively low Urbach energies of 33 meV for (C4H9NH3)2(CH3NH3)2Pb3I10 and 32 meV for (C4H9NH3)2(CH3NH3)3Pb4I13, indicating that the electronic properties are insensitive to the phase impurities.
关键词： phase intergrowth,structural defects,Ruddlesden?Popper,thin films,Organic metal halide,perovskite
更新于2025-09-09 09:28:46
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Rationalizing and Controlling the Surface Structure and Electronic Passivation of Cesium Lead Halide Nanocrystals
摘要： Colloidal lead halide perovskite nanocrystals (NCs) have recently emerged as versatile photonic sources. Their processing and luminescent properties are challenged by the lability of their surfaces, i.e. the interface of the NC core and the ligand shell. On the example of CsPbBr3 NCs, we model the nanocrystal surface structure and its effect on the emergence of trap states using density functional theory. We rationalize the typical observation of a degraded luminescence upon aging or the luminescence recovery upon post-synthesis surface treatments. The conclusions are corroborated by the elemental analysis. We then propose a strategy for healing the surface trap states and for improving the colloidal stability by the combined treatment with didodecyldimethyl ammonium bromide and lead bromide and validate this approach experimentally. This simple procedure results in robust colloids, which are both highly pure and exhibit high photoluminescence quantum yields of up to 95-98%, retained even after 3-4 rounds of washing.
关键词： trap states,didodecyldimethyl ammonium bromide,luminescence recovery,photoluminescence quantum yields,lead bromide,CsPbBr3 NCs,density functional theory,Colloidal lead halide perovskite nanocrystals,surface structure
更新于2025-09-09 09:28:46
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Trap-Mediated Two-Step Sensitization of Manganese Dopants in Perovskite Nanocrystals
摘要： Halide perovskite nanocrystals hold promise for printable optoelectronic and photonic applications. Doping enhances their functionalities and is being investigated for substituting lead with environmentally friendlier elements. The most investigated dopant is Mn2+ that acts as a color center sensitized by the host excitons. The sensitization mechanism is far from understood and no comprehensive picture of the energy-transfer process has been proposed. Similarly, the role of shallow states - particularly abundant in defect tolerant materials - is still unknown. Here, we address this problem via spectroscopic studies at controlled excitation density and temperature on Mn:CsPbCl3 nanocrystals. Our results indicate a two-step process involving exciton localization in a shallow metastable state that mediates the thermally-assisted sensitization of the Mn2+-emission, which is completely quenched for T<200K. At T≤60K, however, such emission surprisingly reappears, suggesting direct energy-transfer from band-edge states. Electron spin resonance supports this picture revealing the signatures of conformational rearrangements below 70K, possibly removing the potential barrier for sensitization. Our results demystify anomalous behaviors of the exciton-to-Mn2+ energy-transfer mechanism and highlight the role of shallow defects in the photophysics of doped perovskite nanostructures.
关键词： Halide perovskite nanocrystals,energy-transfer,spectroscopic studies,Mn2+ dopants,shallow states
更新于2025-09-09 09:28:46