Sublattice Distortion Enabled Strong Interplay between Phonon Vibrations, Electron–Phonon Coupling, and Self-Trapped Excitonic Emissions in Cs2Ag1–xNaxBiCl6 Double Perovskites

AbstractThe performance of perovskite photovoltaics is fundamentally impeded by the presence of undesirable defects that contribute to non-radiative losses within the devices. Although mitigating these losses has been extensively reported by numerous passivation strategies, a detailed understanding of loss origins within the devices remains elusive. Here, we demonstrate that the defect capturing probability estimated by the capture cross-section is decreased by varying the dielectric response, producing the dielectric screening effect in the perovskite. The resulting perovskites also show reduced surface recombination and a weaker electron-phonon coupling. All of these boost the power conversion efficiency to 22.3% for an inverted perovskite photovoltaic device with a high open-circuit voltage of 1.25 V and a low voltage deficit of 0.37 V (a bandgap ~1.62 eV). Our results provide not only an in-depth understanding of the carrier capture processes in perovskites, but also a promising pathway for realizing highly efficient devices via dielectric regulation.

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Reexamination of electron-phonon coupling constant in continuum model by comparison with Boltzmann transport theory

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2021.121309 ◽

2021 ◽

Vol 174 ◽

pp. 121309

Author(s):

Wuli Miao ◽

Moran Wang

Keyword(s):

Continuum Model ◽

Transport Theory ◽

Boltzmann Transport ◽

Coupling Constant ◽

Phonon Coupling ◽

Boltzmann Transport Theory ◽

Electron Phonon Coupling

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Structural phase transition and superconductivity hierarchy in 1T-TaS2 under pressure up to 100 GPa

npj Quantum Materials ◽

10.1038/s41535-021-00320-x ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Qing Dong ◽

Quanjun Li ◽

Shujia Li ◽

Xuhan Shi ◽

Shifeng Niu ◽

...

Keyword(s):

Structural Phase ◽

Transition Metal Dichalcogenides ◽

Phonon Coupling ◽

Structural Phase Transitions ◽

Strong Electron ◽

Electron Phonon Coupling ◽

Increasing Trend ◽

Metal Dichalcogenides ◽

Dome Shape ◽

Enhanced Superconductivity

AbstractThe adoption of high pressure not only reinforces the comprehension of the structure and exotic electronic states of transition metal dichalcogenides (TMDs) but also promotes the discovery of intriguing phenomena. Here, 1T-TaS2 was investigated up to 100 GPa, and re-enhanced superconductivity was found with structural phase transitions. The discovered I4/mmm TaS2 presents strong electron–phonon coupling, revealing a good superconductivity of the nonlayered structure. The P–T phase diagram shows a dome shape centered at ~20 GPa, which is attributed to the distortion of the 1T structure. Accompanied by the transition to nonlayered structure above 44.5 GPa, the superconducting critical temperature shows an increasing trend and reaches ~7 K at the highest studied pressure, presenting superior superconductivity compared to the original layered structure. It is unexpected that the pressure-induced re-enhanced superconductivity was observed in TMDs, and the transition from a superconductor with complicated electron-pairing mechanism to a phonon-mediated superconductor would expand the field of pressure-modified superconductivity.

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Ab Initio Study of the Electron–Phonon Coupling in Ultrathin Al Layers

Journal of Low Temperature Physics ◽

10.1007/s10909-021-02574-y ◽

2021 ◽

Vol 203 (1-2) ◽

pp. 180-193

Author(s):

S. Giaremis ◽

Ph. Komninou ◽

Th. Karakostas ◽

J. Kioseoglou

Keyword(s):

Ab Initio ◽

Ab Initio Study ◽

Phonon Coupling ◽

Electron Phonon Coupling

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Resonance and antiresonance in Raman scattering in GaSe and InSe crystals

Scientific Reports ◽

10.1038/s41598-020-79411-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

M. Osiekowicz ◽

D. Staszczuk ◽

K. Olkowska-Pucko ◽

Ł. Kipczak ◽

M. Grzeszczyk ◽

...

Keyword(s):

Raman Scattering ◽

Temperature Effect ◽

Band Gap ◽

Raman Spectra ◽

Quantum Interference ◽

Optical Band Gap ◽

Phonon Coupling ◽

Phonon Modes ◽

Electron Phonon Coupling ◽

Resonant Raman

AbstractThe temperature effect on the Raman scattering efficiency is investigated in $$\varepsilon$$ ε -GaSe and $$\gamma$$ γ -InSe crystals. We found that varying the temperature over a broad range from 5 to 350 K permits to achieve both the resonant conditions and the antiresonance behaviour in Raman scattering of the studied materials. The resonant conditions of Raman scattering are observed at about 270 K under the 1.96 eV excitation for GaSe due to the energy proximity of the optical band gap. In the case of InSe, the resonant Raman spectra are apparent at about 50 and 270 K under correspondingly the 2.41 eV and 2.54 eV excitations as a result of the energy proximity of the so-called B transition. Interestingly, the observed resonances for both materials are followed by an antiresonance behaviour noticeable at higher temperatures than the detected resonances. The significant variations of phonon-modes intensities can be explained in terms of electron-phonon coupling and quantum interference of contributions from different points of the Brillouin zone.

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