scholarly journals Excitation Wavelength and Intensity-Dependent Multiexciton Dynamics in CsPbBr3 Nanocrystals

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 463
Author(s):  
Chaochao Qin ◽  
Zhinan Jiang ◽  
Zhongpo Zhou ◽  
Yufang Liu ◽  
Yuhai Jiang
Keyword(s):  
Auger Recombination ◽  
Transient Absorption ◽  
Photoluminescence Spectroscopy ◽  
Transient Absorption Spectroscopy ◽  
Excitation Wavelength ◽  
Time Resolved ◽  
Recombination Lifetime ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Femtosecond Transient Absorption

CsPbBr3 has attracted great attention due to unique optical properties. The understanding of the multiexciton process is crucial for improving the performance of the photoelectric devices based on CsPbBr3 nanocrystals. In this paper, the ultrafast dynamics of CsPbBr3 nanocrystals is investigated by using femtosecond transient absorption spectroscopy. It is found that Auger recombination lifetime increases with the decrease of the excitation intensity, while the trend is opposite for the hot-exciton cooling time. The time of the hot-carriers cooling to the band edge is increased when the excitation energy is increased from 2.82 eV (440 nm) to 3.82 eV (325 nm). The lifetime of the Auger recombination reaches the value of 126 ps with the excitation wavelength of 440 nm. The recombination lifetime of the single exciton is about 7 ns in CsPbBr3 nanocrystals determined by nanosecond time-resolved photoluminescence spectroscopy. The exciton binding energy is 44 meV for CsPbBr3 nanocrystals measured by the temperature-dependent steady-state photoluminescence spectroscopy. These findings provide a favorable insight into applications such as solar cells and light-emitting devices based on CsPbBr3 nanocrystals.

Charge carrier kinetics of carbon nitride colloid: a femtosecond transient absorption spectroscopy study

2016 ◽  
Vol 18 (22) ◽  
pp. 14904-14910 ◽  
Author(s):  
Huiyu Zhang ◽  
Yaping Chen ◽  
Rong Lu ◽  
Ruiyu Li ◽  
Anchi Yu
Keyword(s):  
Charge Carrier ◽  
Carbon Nitride ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Spectroscopy Study ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Femtosecond Transient Absorption ◽  
Femtosecond Transient Absorption Spectroscopy ◽  
Kinetics Of

The charge carrier kinetics of carbon nitride colloid was investigated using a combination of femtosecond transient absorption and picosecond time-resolved fluorescence spectroscopy.

EMI Series Mechanistic Investigation of a Visible Light Mediated Dehalogenation/Cyclisation Reaction using Iron(III), Iridium(III) and Ruthenium(II) Photosensitizers

2021 ◽  
Author(s):  
Akin Aydogan ◽  
Rachel Bangle ◽  
Simon De Kreijger ◽  
John Dickenson ◽  
Michael L Singleton ◽  
...  
Keyword(s):  
Steady State ◽  
Visible Light ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Time Resolved ◽  
Femtosecond Transient Absorption ◽  
Mechanistic Investigation ◽  
Femtosecond Transient Absorption Spectroscopy ◽  
Visible Light Driven ◽  
Time Resolved Infrared Spectroscopy

The mechanism of a visible light-driven dehalogenation/cyclization reaction was investigated using ruthenium(II), iridium(III) and iron(III) photosensitizers by means of steady-state photoluminescence, time-resolved infrared spectroscopy, and nanosecond/femtosecond transient absorption spectroscopy. The...

scholarly journals Probing the ultrafast dynamics in nanomaterial complex systems by femtosecond transient absorption spectroscopy

2016 ◽  
Vol 4 ◽  
Author(s):  
Qun Zhang ◽  
Yi Luo
Keyword(s):  
Complex Systems ◽  
Absorption Spectroscopy ◽  
Ultrafast Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Ultrafast Dynamics ◽  
Time Resolved ◽  
The Past ◽  
Femtosecond Transient Absorption ◽  
Consistent Information

Over the past decade the integration of ultrafast spectroscopy with nanoscience has greatly propelled the development of nanoscience, as the key information gleaned from the mechanistic studies with the assistance of ultrafast spectroscopy enables a deeper understanding of the structure–function interplay and various interactions involved in the nanosystems. This mini-review presents an overview of the recent advances achieved in our ultrafast spectroscopy laboratory that address the ultrafast dynamics and related mechanisms in several representative nanomaterial complex systems by means of femtosecond time-resolved transient absorption spectroscopy. We attempt to convey instructive, consistent information regarding the important processes, pathways, dynamics, and interactions involved in the nanomaterial complex systems, most of which exhibit excellent performance in photocatalysis.

scholarly journals Anti-Kasha Behavior of 3-Hydroxyflavone and Its Derivatives

2021 ◽  
Vol 22 (20) ◽  
pp. 11103
Author(s):  
Ka Wa Fan ◽  
Hoi Ling Luk ◽  
David Lee Phillips
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Transient Absorption ◽  
Intramolecular Proton Transfer ◽  
Transient Absorption Spectroscopy ◽  
Excitation Wavelength ◽  
Computational Studies ◽  
Femtosecond Transient Absorption ◽  
First Excited State ◽  
Experimental Findings

Excited state intramolecular proton transfer (ESIPT) in 3-hydroxyflavone (3HF) has been known for its dependence on excitation wavelength. Such a behavior violates Kasha’s rule, which states that the emission and photochemistry of a compound would only take place from its lowest excited state. The photochemistry of 3HF was studied using femtosecond transient absorption spectroscopy at a shorter wavelength excitation (266 nm), and these new experimental findings were interpreted with the aid of computational studies. These new results were compared with those from previous studies that were obtained with a longer wavelength excitation and show that there exists a pathway of proton transfer that bypasses the normal first excited state from the higher excited state to the tautomer from first excited state. The experimental data correlate with the electron density difference calculations such that the proton transfer process is faster on the longer excitation wavelength than compared to the shorter excitation wavelength.

scholarly journals Comparing Donor- and Acceptor-Originated Exciton Dynamics in Non-Fullerene Acceptor Blend Polymeric Systems

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1770
Author(s):  
Chan Im ◽  
Sang-Woong Kang ◽  
Jeong-Yoon Choi ◽  
Jongdeok An
Keyword(s):  
Flexible Electronics ◽  
Transient Absorption ◽  
Film Formation ◽  
Transient Absorption Spectroscopy ◽  
Excitation Wavelength ◽  
Polymeric Systems ◽  
Donor And Acceptor ◽  
Novel Material ◽  
Spectrally Resolved ◽  
Energy Strategies

Non-fullerene type acceptors (NFA) have gained attention owing to their spectral extension that enables efficient solar energy capturing. For instance, the solely NFA-mediated absorbing region contributes to the photovoltaic power conversion efficiency (PCE) as high as ~30%, in the case of the solar cells comprised of fluorinated materials, PBDB-T-2F and ITIC-4F. This implies that NFAs must be able to serve as electron donors, even though they are conventionally assigned as electron acceptors. Therefore, the pathways of NFA-originated excitons need to be explored by the spectrally resolved photovoltaic characters. Additionally, excitation wavelength dependent transient absorption spectroscopy (TAS) was performed to trace the nature of the NFA-originated excitons and polymeric donor-originated excitons separately. Unique origin-dependent decay behaviors of the blend system were found by successive comparing of those solutions and pristine films which showed a dramatic change upon film formation. With the obtained experimental results, including TAS, a possible model describing origin-dependent decay pathways was suggested in the framework of reaction kinetics. Finally, numerical simulations based on the suggested model were performed to verify the feasibility, achieving reasonable correlation with experimental observables. The results should provide deeper insights in to renewable energy strategies by using novel material classes that are compatible with flexible electronics.

scholarly journals Ultrafast nonequilibrium dynamic process of separate electron and hole during exciton formation in few-layer tungsten disulfide

2021 ◽  
Author(s):  
Junjie Chen ◽  
Sen Guo ◽  
Dabin Lin ◽  
Zhaogang Nie ◽  
Chung-Che Huang ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Dynamic Process ◽  
Formation Process ◽  
Transient Absorption ◽  
Tungsten Disulfide ◽  
Transient Absorption Spectroscopy ◽  
Femtosecond Transient Absorption ◽  
Nonequilibrium Dynamic ◽  
Femtosecond Transient Absorption Spectroscopy ◽  
Separate Electron

Femtosecond transient absorption spectroscopy has been employed to unravel separate initial nonequilibrium dynamic process of photo-injected electrons and holes during the formation process of the lowest excitons at the K-valley...

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