Perovskites have been recognized as a class of promising materials for optoelectronic devices. We intentionally include excessive Cs cations in precursors in the synthesis of perovskite CsPbBr nanocrystals and investigate how the Cs cations influence the lattice strain in these perovskite nanocrystals. Upon light illumination, the lattice strain due to the addition of alkali metal Cs cations can be compensated by light-induced lattice expansion. When the Cs cation in precursors is about 10% excessive, the electron-phonon coupling strength can be reduced by about 70%, and the carrier cooling can be slowed down about 3.5 times in lead halide perovskite CsPbBr nanocrystals. This work reveals a new understanding of the role of Cs cations, which take the A-site in ABX perovskite and provide a new way to improve the performance of perovskites and their practical devices further.
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http://dx.doi.org/10.3390/nano13243134 | DOI Listing |
Phys Rev Lett
December 2024
Chalmers University of Technology, Department of Physics, 412 96 Göteborg, Sweden.
The phonon inverse Faraday effect describes the emergence of a dc magnetization due to circularly polarized phonons. In this work we present a microscopic formalism for the phonon inverse Faraday effect. The formalism is based on time-dependent second order perturbation theory and electron phonon coupling.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China.
Although a substantial amount of research has been conducted to unravel the structural configurations of selenium under pressure, the exquisite sensitivity of selenium's p-orbital electrons to this external force, leading to a plethora of structural variations, leaves several intermediary phases still shrouded in mystery. We, herein, systematically identify the structural and electronic transformations of selenium under high pressure up to 300 GPa, employing crystal structure prediction in conjunction with first-principles calculations. Our results for the transition sequence (321 → 2/ → 3̄ → 3̄) of selenium are in good agreement with experimental ones.
View Article and Find Full Text PDFJ Phys Chem Lett
January 2025
State Key Laboratory of Organic Electronics and Information Displays, Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, China.
Halide perovskite optoelectronic devices achieve high energy conversion efficiencies. However, their efficiency decreases significantly with an increase in temperature. This decline is likely caused by changes in nonradiative recombination and electron-phonon coupling, which remain underexplored.
View Article and Find Full Text PDFNanomaterials (Basel)
January 2025
Department of Physics and Natural Science Research Institute, University of Seoul, Seoul 02504, Republic of Korea.
Bulk n-type SrTiO (STO) has long been known to possess a superconducting ground state at an exceptionally dilute carrier density. This has raised questions about the applicability of the BCS-Eliashberg paradigm with its underlying adiabatic assumption. However, recent experimental reports have set the pairing gap to the critical temperature (Tc) ratio at the BCS value for superconductivity in Nb-doped STO, even though the adiabaticity condition the BCS pairing requires is satisfied over the entire superconducting dome only by the lowest branch of optical phonons.
View Article and Find Full Text PDFNanomaterials (Basel)
January 2025
Hunan Key Laboratory of Super-Microstructure and Ultrafast Process, School of Physics, Central South University, Changsha 410083, China.
Two-dimensional (2D) layered materials have received much attention due to the unique properties stemming from their van der Waals (vdW) interactions, quantum confinement, and many-body interactions of quasi-particles, which drive their exotic optical and electronic properties, making them critical in many applications. Here, we review our past years' findings, focusing on many-body interactions in 2D layered materials, including phonon anharmonicity, electron-phonon coupling (), exciton dynamics, and phonon anisotropy based on temperature (polarization)-dependent Raman spectroscopy and Photoluminescence (PL). Our review sheds light on the role of quasi-particles in tuning the material properties, which could help optimize 2D materials for future applications in electronic and optoelectronic devices.
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