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Ultrafast Interfacial Charge Transfer of Cesium Lead Halide Perovskite Films CsPbX3 (X = Cl, Br, I) with Different Halogen Mixing
摘要： Understanding the interfacial charge transfer of the photoinduced transients of all-inorganic cesium lead halide perovskites (CsPbX3; X = Cl, Br, I) is critical for their photovoltaic applications. Ultrafast dynamics can provide comprehensive information about the transient behavior of the carriers and their transfer mechanism in the materials. In this work, the interfacial charge transfer of CsPbX3 films assembled with TiO2 with different halogen doping ratios was studied using femtosecond transient absorption (TA) spectroscopy combined with global analysis. Four subsequent decay processes after photoexcitation were obtained, including hot carrier cooling, free exciton forming, electron transfer, and charge recombination. The results indicate that the time constant of the interfacial electron transfer varies with the location of the trap state of these perovskites and the relative energy of CBs in the perovskite and TiO2 and that the time constant of the charge recombination can be attributed to the electron–hole interactions. These interpretations are supported by calculations based on first-principles density functional theory (DFT). Greater iodine doping in such perovskite CsPbX3/TiO2 systems increases the time constants of the electron transfer and charge recombination, which suggests that all-inorganic perovskite CsPbX3 with a high iodine content is favorable for improving the power conversion efficiency of solar cells.
关键词： cesium lead halide perovskite,transient absorption,global analysis,interfacial charge transfer
更新于2025-09-23 15:21:01
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One-step Co-evaporation of All-Inorganic Perovskite Thin Films with Room Temperature Ultralow Amplified Spontaneous Emission Threshold and Air-stability
摘要： Inorganic cesium lead halide perovskite has been successfully applied in optoelectronic field due to its remarkable optical gain properties. Unfortunately, conventional solution-processed CsPbX3 films suffer unavoidable pinhole defects and poor surface morphology, severely limiting their performance on amplified spontaneous emission (ASE) and lasing application. Herein, a dual-source thermal evaporation approach is explored in our work to achieve a uniform and high-coverage CsPbX3 polycrystalline thin film. It is found that the one-step co-evaporated CsPbBr3 (OC-CsPbBr3) thin films without post-annealing exhibit an ultralow ASE threshold of ~ 3.3 μJ/cm2 and gain coefficient above 300 cm-1. The coexistence of cubic and orthorhombic phases in this materials naturally form an energy cascade for the exciton transfer process, which enables rapid accumulation of excitons. Stable ASE intensity without degradation for at least 7 hours is also realized from OC-CsPbBr3 thin films under continuous excitation, which is superior to that in the solution-processed CsPbBr3 thin film. Notably, a Fabry-Perot (F-P) cavity laser based on the OC-CsPbBr3 thin film is first achieved, featuring an ultralow lasing threshold (1.7 μJ/cm2) and directional output (beam divergence of ~ 3.8°). This work highlights the noteworthy optical properties of OC-CsPbBr3 thin films, leading to potential available applications in the integrated optoelectronic chips.
关键词： amplified spontaneous emission,Cesium lead halide perovskite,vapor deposition,long-term stability,thin films
更新于2025-09-23 15:21:01
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Controllable synthesis of all inorganic lead halide perovskite nanocrystals and white light-emitting diodes based on CsPbBr3 nanocrystals
摘要： The colloidal cesium lead halide perovskite nanocrystals (NCs) have attracted much attention over the past five years as a promising class of material with potential application in wide-color-gamut backlight display because of their high photoluminescence quantum yield (PLQY) and narrow-band emission (full-width at half-maximum, FWHM < 35 nm). To controllably synthesize perovskite NCs, the effects of reaction temperature and reaction time on structure, morphology, particle size and photoluminescence (PL) properties of the NCs were systematically investigated in this article. Based on these results, the formation kinetics of the perovskite NCs was analyzed and disclosed in further. Finally, a white light-emitting diode (WLED) was prepared by using synthesized CsPbBr3 NCs and K2SiF6:Mn4+ phosphors as the color converters. The WLED exhibits the bright white emission with a CIE chromaticity coordinate of (0.389, 0.376) and a wide color gamut of 123% of NTSC, indicating a potential application in the field of wide color gamut displays in the future.
关键词： Cesium lead halide perovskite,white light-emitting diodes,photoluminescent,hot-injection method,nanocrystals
更新于2025-09-23 15:19:57
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Exploring the surface chemistry of cesium lead halide perovskite nanocrystals
摘要： Colloidal nanocrystals (NCs) of cesium lead halide perovskites (CsPbX3, X = Cl, Br or I) are emerging as an exciting class of optoelectronic materials, but the retention of their colloidal and structural integrity during isolation, purification and handling still represents a critical issue. The impelling questions concerning their intrinsic chemical instability are connected to the dynamic nature of the bonding between the inorganic surface and the long-chain capping ligands. However, the key aspects of CsPbX3's surface chemistry that directly impact their stability remain elusive. In this contribution, we provide an in-depth investigation of the surface properties of differently composed CsPbX3 NCs, prepared by traditional hot-injection methods. The study, mainly relying on solution NMR spectroscopy, is backed up by elemental analysis as well as morphological, structural and optical investigations. We ascertained that the nature of the ligand adsorption/desorption processes at the NC surface is dependent on its elemental composition, thus explaining the origin of the instability afflicting CsPbI3 NCs. We also evaluated the effect of NC purification as well as of the degradation pathways involving the organic shell on the surface chemistry of CsPbX3 NCs. This study paves the way for new post-functionalization strategies for this promising class of nanomaterials.
关键词： surface chemistry,colloidal stability,degradation pathways,cesium lead halide perovskite nanocrystals,purification,ligand adsorption/desorption,NMR spectroscopy
更新于2025-09-19 17:15:36
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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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[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) - Room-Temperature Synthesis of Cesium Lead Halide Perovskite Nanorods
摘要： Low-dimensional materials attract much attention because of their unique and outstanding properties in optical and electronic products, giving a promising class of materials for optoelectronic applications. A facile synthesis method of CsPbBr3 nanorods (NRs) was presented in this paper. The nanorods have a one-dimensional (1D) scale, a high photoluminescence quantum yield (PLQY, 60%) and a narrow FWHM. By tuning the ratio of organic ligands, the CsPbBr3 NRs with the diameter of less than 20 nm and length up to several hundred nanometers were obtained. Moreover, because of the quantum confinement effects, a large blue-shift have happened in PL spectra. A light-emitting diode (LED) device was fabricated with our synthesized CsPbBr3 NRs. The LED device showed a strong green emission. All of these shows the ability of halide perovskite nanocrystals for applications on photoelectron, such as optical communication, display, lightning and so on.
关键词： formation mechanism,cesium lead halide perovskite nanorods,light-emitting diode
更新于2025-09-09 09:28:46