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Spectrally Resolved Ultrafast Exciton Transfer in Mixed Perovskite Quantum Wells
摘要： Solution-processed perovskite quantum wells have been used to fabricate increasingly efficient and stable optoelectronic devices. Little is known about the dynamics of photogenerated excitons in perovskite quantum wells within the first few hundred femtoseconds – a crucial timescale on which energy and charge transfer processes may compete. Here we use ultrafast transient absorption and two-dimensional electronic spectroscopy to clarify the movement of excitons and charges in reduced-dimensional perovskite solids. We report excitonic funneling from strongly to weakly confined perovskite quantum wells within 150 fs, facilitated by strong spectral overlap and orientational alignment among neighboring wells. This energy transfer happens on timescales orders of magnitude faster than charge transfer, which we find to occur instead over 10 - 100s of picoseconds. Simulations of both F?rster-type interwell exciton transfer and free carrier charge transfer are in agreement with these experimental findings, with theoretical exciton transfer calculated to occur in 100s of fs.
关键词： energy transfer,Carrier,metal halide perovskite,two-dimensional electronic spectroscopy,layered perovskite,dynamics
更新于2025-09-23 15:23:52
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Synthesis and X-ray absorption spectroscopic analysis of exfoliated perovskite oxynitride nanosheets obtained from LiLaTa2O6.15N0.57 precursor
摘要： Layered perovskite oxynitride LiLaTa2O6.15N0.57 with Dion-Jacobson phase was successfully exfoliated into colloidal suspension by using proton-exchange reaction and followed intercalation of ethylamine and tetrabutylammonium ion. According to the X-ray di?raction pattern, a basal spacing of the layered perovskite oxynitride concomitantly increased as the intercalation reaction with bulky cations proceeded. Transmission electron microscopy and atomic force microscopy analysis indicated that the exfoliated perovskite oxynitride was composed of single-layered and multi-stacked nanoplatelets. UV–vis di?use re?ectance showed that the self-reassembled perovskite oxynitride nanosheet also had characteristic absorption in a visible range, revealing that visible light harvesting property of the perovskite oxynitride maintained even after exfoliation and subsequent reassembling reaction. Extended X-ray absorption ?ne structure (EXAFS) analysis of samples clearly showed that structural disorder upon intercalation reaction resulted in damping of EXAFS oscillation, suggesting nanosized feature of the exfoliated nanosheet.
关键词： Exfoliation,XANES,Layered perovskite oxynitride,EXAFS,Intercalation
更新于2025-09-23 15:21:21
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Two-dimensional Ruddlesdena??Popper layered perovskite for light-emitting diodes
摘要： Solution-processed metal halide perovskite light-emitting diodes (PeLEDs) have attracted extensive attention due to the great potential application in energy-efficient lighting and displays. Two-dimensional Ruddlesden–Popper (2DRP) layered perovskites exhibit high photoluminescence quantum efficiency, improved film morphology, and enhanced operational stability over their three-dimensional counterparts, making them attractive for high-performance PeLEDs. In addition, 2DRP perovskite materials with a tunable exciton binding energy are suitable for preparing PeLEDs with color-tunability. In this perspective, we first introduce the merits of the 2DRP layered perovskites in terms of their structural characteristics. The progress in 2DRP PeLEDs is then reviewed. The challenges and new opportunities of the PeLEDs are finally discussed. We hope to open up new perspectives for rational designs of the 2DRP perovskite materials for PeLEDs with unprecedented efficiency and stability.
关键词： operational stability,film morphology,photoluminescence quantum efficiency,Two-dimensional Ruddlesden–Popper layered perovskite,color-tunability,light-emitting diodes
更新于2025-09-19 17:13:59
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Physisorption induced p-xylene gas-sensing performance of (C4H9NH3)2PbI4 layered perovskite
摘要： A novel organic-inorganic layered perovskite compound (C4H9NH3)2PbI4 has been synthesized through a simple and high-yield solution method. For the first time, this layered perovskite was used as a candidate material for gas sensors. Gas sensors based on (C4H9NH3)2PbI4 provided unique gas-sensing properties toward 1 - 800 ppm p-xylene (p-C8H10) at the working temperature of 140 °C, including fast response, quick response-recovery, good selectivity and repeatability. The as-prepared (C4H9NH3)2PbI4 gas sensor can detect as low as 1 ppm concentration of p-xylene with a response of 11.8 at 140 °C. In situ diffuse reflectance Fourier transform infrared (DRFTIR) measurement shows that the p-xylene sensing mechanism can be mainly attributed to physical adsorption, which is different from other common gas-sensing metal oxides that are based on adsorption-redox-desorption mechanism.
关键词： (C4H9NH3)2PbI4,physisorption,layered perovskite,gas sensor,organic-inorganic,p-xylene
更新于2025-09-10 09:29:36