Metal halide perovskites (MHPs) have attracted attention because of their high optoelectronic performance that is fundamentally rooted in the unusual properties of MHP defects. By developing an ab initio-based machine-learning force field, we sample the structural dynamics of MHPs on a nanosecond time scale and show that halide vacancies create midgap trap states in the MHP bulk but not on a surface. Deep traps result from Pb-Pb dimers that can form across the vacancy in only the bulk. The required shortening of the Pb-Pb distance by nearly 3 Å is facilitated by either charge trapping or 50 ps thermal fluctuations. The large-scale structural deformations are possible because MHPs are soft. Halide vacancies on the MHP surface create no deep traps but separate electrons from holes, keeping the charges mobile. This is particularly favorable for MHP quantum dots, which do not require sophisticated surface passivation to emit light and blink less than quantum dots formed from traditional inorganic semiconductors.
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January 2025
College of Physics and Optoelectronic Engineering, Harbin Engineering University, Harbin, 150001, P. R. China.
Currently, CsPbI quantum dots (QDs) based light-emitting diodes (LEDs) are not well suited for achieving high efficiency and operational stability due to the binary-precursor method and purification process, which often results in the nonstoichiometric ratio of Cs/Pb/I. This imbalance leads to amounts of iodine vacancies, inducing severe non-radiative recombination processes and phase transitions of QDs. Herein, red-emitting CsPbI QDs are reported with excellent optoelectronic properties and stability based on the synergistic effects of halide-rich modulation passivation and lattice repair.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
College of Physics and Electronic Engineering, Hainan Normal University, Haikou 571158, China.
Perovskite heterostructures have attracted wide interest for their photovoltaic and optoelectronic applications. The interdiffusion of halide anions leads to the poor stability and shorter lifetime of the halide perovskite heterostructures. Covering organic cations on the surface of perovskite heterostructures, the diffusion of ions can effectively be suppressed.
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
Key Laboratory for High Efficiency Energy Conversion Science and Technology of Henan Province, International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, School of Physics and Electronics, Henan University, Kaifeng, 475004, P. R. China.
Multimode luminescent materials exhibit tunable photon emissions under different excitation or stimuli channels, endowing them high encoding capacity and confidentiality for anti-counterfeiting and encryption. Achieving multimode luminescence into a stable single material presents a promising but remains a challenge. Here, the downshifting/upconversion emissions, color-tuning persistent luminescence (PersL), temperature-dependent multi-color emissions, and hydrochromism are integrated into Er ions doped CsNaYbCl nanocrystals (NCs) by leveraging shallow defect levels and directed energy migration.
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, Shaanxi Key Laboratory for Advanced Energy Devices, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an, 710119, P. R. China.
Understanding the oxygen evolution reaction (OER) mechanism is pivotal for improving the overall efficiency of water electrolysis. Despite methylammonium lead halide perovskites (MAPbX) have shown promising OER performance due to their soft-lattice nature that allows lattice-oxygen oxidation of active α-PbO layer surface, the role of A-site MA or X-site elements in the electrochemical reconstruction and OER mechanisms has yet to be explored. Here, it is demonstrated that the OER mechanism of perovskite@zeolite composites is intrinsically dominated by the A-site group of lead-halide perovskites, while the type of X-site halogen is crucial for the reconstruction kinetics of the composites.
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January 2025
Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, Vassilika Vouton, Heraklion, 70013, Greece.
Metal halide perovskites (MHPs) have attracted significant attention owing to their simple manufacturing process and unique optoelectronic properties. Their reversible electrical or optical property changes in response to oxidizing or reducing environments make them prospective materials for gas detection technologies. Despite advancements in perovskite-based sensor research, the mechanisms behind perovskite-gas interactions, vital for sensor performance, are still inconclusive.
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