Difference in hot carrier cooling rate between Langmuir–Blodgett and drop cast PbS QD films due to strong electron–phonon coupling

Nanoscale ◽  
2017 ◽  
Vol 9 (43) ◽  
pp. 17133-17142 ◽  
Author(s):  
Wenkai Cao ◽  
Lin Yuan ◽  
Rob Patterson ◽  
Xiaoming Wen ◽  
Patrick C. Tapping ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Phonon Coupling ◽  
Lead Sulphide ◽  
Strong Electron ◽  
Hot Carrier ◽  
Langmuir Blodgett ◽  
Femtosecond Transient Absorption ◽  
Electron Phonon Coupling ◽  
Langmuir Blodgett Films

The carrier dynamics of lead sulphide quantum dot (PbS QD) drop cast films and closely packed ordered Langmuir–Blodgett films are studied with ultra-fast femtosecond transient absorption spectroscopy.

scholarly journals Anomalous phonon relaxation in Au333(SR)79 nanoparticles with nascent plasmons

2019 ◽  
Vol 116 (27) ◽  
pp. 13215-13220 ◽  
Author(s):  
Tatsuya Higaki ◽  
Meng Zhou ◽  
Guiying He ◽  
Stephen D. House ◽  
Matthew Y. Sfeir ◽  
...  
Keyword(s):  
Relaxation Process ◽  
Transient Absorption ◽  
Quantum Effect ◽  
Transient Absorption Spectroscopy ◽  
Phonon Coupling ◽  
Size Regime ◽  
Femtosecond Transient Absorption ◽  
Electron Phonon Coupling ◽  
Future Work ◽  
Broad Interest

Research on plasmons of gold nanoparticles has gained broad interest in nanoscience. However, ultrasmall sizes near the metal-to-nonmetal transition regime have not been explored until recently due to major synthetic difficulties. Herein, intriguing electron dynamics in this size regime is observed in atomically precise Au333(SR)79 nanoparticles. Femtosecond transient-absorption spectroscopy reveals an unprecedented relaxation process of 4–5 ps—a fast phonon–phonon relaxation process, together with electron–phonon coupling (∼1 ps) and normal phonon–phonon coupling (>100 ps) processes. Three types of –R capped Au333(SR)79 all exhibit two plasmon-bleaching signals independent of the –R group as well as solvent, indicating plasmon splitting and quantum effect in the ultrasmall core of Au333(SR)79. This work is expected to stimulate future work on the transition-size regime of nanometals and discovery of behavior of nascent plasmons.

scholarly journals Photophysics and spectroscopy of metal particles

2000 ◽  
Vol 72 (1-2) ◽  
pp. 189-197 ◽  
Author(s):  
José H. Hodak ◽  
Arnim Henglein ◽  
Gregory V. Hartland
Keyword(s):  
Transient Absorption ◽  
Classical Mechanics ◽  
Transient Absorption Spectroscopy ◽  
Metal Particles ◽  
Characteristic Time Scale ◽  
Phonon Coupling ◽  
Particle Volume ◽  
Plasmon Band ◽  
Free Electron Density ◽  
Electron Phonon Coupling

This paper describes our recent work using ultrafast laser spectroscopy to examine the fundamental properties of metal particles. Two studies are presented. First, the characteristic time scale for electron-phonon coupling in Au particles with sizes between 2 and 120 nm has been examined by bleach recovery measurements. These experiments show that the coupling between the electrons and phonons is independent of particle size, to within the signal-to-noise of our experiments. We have also used transient absorption spectroscopy to examine the low-frequency "breathing" modes of the Au particles. These modes are impulsively excited by the rapid lattice heating that accompanies electron-phonon coupling. The breathing motion contributes to the transient absorption signal because the position of the plasmon band depends on the free electron density and, thus, the particle volume. The measured frequencies are inversely proportional to the radius, and almost exactly match the predictions of classical mechanics calculations for Au.

Pronounced exciton and coherent phonon dynamics in BiI3

2018 ◽  
Vol 20 (16) ◽  
pp. 10677-10685 ◽  
Author(s):  
Mirko Scholz ◽  
Kawon Oum ◽  
Thomas Lenzer
Keyword(s):  
Transient Absorption ◽  
Coherent Phonon ◽  
Phonon Coupling ◽  
Strong Electron ◽  
Electron Phonon Coupling ◽  
Phonon Dynamics

Long-lived coherent oscillations in transient absorption signals of BiI3 suggest strong electron–phonon coupling in this material for photovoltaics.

scholarly journals Efficient Intraband Hot Carrier Relaxation in the Perovskite Semiconductor Cs1–xRbxSnI3 Mediated by Strong Electron–Phonon Coupling

2018 ◽  
Vol 122 (36) ◽  
pp. 20669-20675 ◽  
Author(s):  
M. Monti ◽  
S. X. Tao ◽  
M. Staniforth ◽  
A. Crocker ◽  
E. Griffin ◽  
...  
Keyword(s):  
Phonon Coupling ◽  
Strong Electron ◽  
Carrier Relaxation ◽  
Hot Carrier ◽  
Electron Phonon Coupling

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

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.

scholarly journals Manipulation of hot carrier cooling dynamics in two-dimensional Dion–Jacobson hybrid perovskites via Rashba band splitting

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jun Yin ◽  
Rounak Naphade ◽  
Partha Maity ◽  
Luis Gutiérrez-Arzaluz ◽  
Dhaifallah Almalawi ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Phonon Scattering ◽  
Transient Absorption Spectroscopy ◽  
Band Model ◽  
Two Dimensional ◽  
Spintronic Devices ◽  
Hot Carrier ◽  
Band Splitting ◽  
Perovskite Materials ◽  
Spin Polarized

AbstractHot-carrier cooling processes of perovskite materials are typically described by a single parabolic band model that includes the effects of carrier-phonon scattering, hot phonon bottleneck, and Auger heating. However, little is known (if anything) about the cooling processes in which the spin-degenerate parabolic band splits into two spin-polarized bands, i.e., the Rashba band splitting effect. Here, we investigated the hot-carrier cooling processes for two slightly different compositions of two-dimensional Dion–Jacobson hybrid perovskites, namely, (3AMP)PbI4 and (4AMP)PbI4 (3AMP = 3-(aminomethyl)piperidinium; 4AMP = 4-(aminomethyl)piperidinium), using a combination of ultrafast transient absorption spectroscopy and first-principles calculations. In (4AMP)PbI4, upon Rashba band splitting, the spin-dependent scattering of hot electrons is responsible for accelerating hot-carrier cooling at longer delays. Importantly, the hot-carrier cooling of (4AMP)PbI4 can be extended by manipulating the spin state of the hot carriers. Our findings suggest a new approach for prolonging hot-carrier cooling in hybrid perovskites, which is conducive to further improving the performance of hot-carrier-based optoelectronic and spintronic devices.

scholarly journals Direct observation of excitonic instability in Ta2NiSe5

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kwangrae Kim ◽  
Hoon Kim ◽  
Jonghwan Kim ◽  
Changil Kwon ◽  
Jun Sung Kim ◽  
...  
Keyword(s):  
Phase Transition ◽  
Direct Observation ◽  
Structural Phase ◽  
Temperature Phase ◽  
Phonon Coupling ◽  
Strong Electron ◽  
Weiss Temperature ◽  
Excitonic Insulator ◽  
Electron Phonon Coupling ◽  
Low Temperature Phase

AbstractCoulomb attraction between electrons and holes in a narrow-gap semiconductor or a semimetal is predicted to lead to an elusive phase of matter dubbed excitonic insulator. However, direct observation of such electronic instability remains extremely rare. Here, we report the observation of incipient divergence in the static excitonic susceptibility of the candidate material Ta2NiSe5 using Raman spectroscopy. Critical fluctuations of the excitonic order parameter give rise to quasi-elastic scattering of B2g symmetry, whose intensity grows inversely with temperature toward the Weiss temperature of TW ≈ 237 K, which is arrested by a structural phase transition driven by an acoustic phonon of the same symmetry at TC = 325 K. Concurrently, a B2g optical phonon becomes heavily damped to the extent that its trace is almost invisible around TC, which manifests a strong electron-phonon coupling that has obscured the identification of the low-temperature phase as an excitonic insulator for more than a decade. Our results unambiguously reveal the electronic origin of the phase transition.

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