Investigation of ligand effects on exciton recombination in PbS nanoparticles

2011 ◽  
Vol 89 (3) ◽  
pp. 339-346 ◽  
Author(s):  
Jennifer M. Zemke ◽  
Thomas E. Novet ◽  
David R. Tyler
Keyword(s):  
Transient Absorption ◽  
Decay Rates ◽  
Transient Absorption Spectroscopy ◽  
Absorption Data ◽  
Pbs Nanoparticles ◽  
Nonradiative Decay ◽  
Femtosecond Transient Absorption ◽  
Ligand Shell ◽  
Highly Sensitive ◽  
Exciton Recombination

Multiple exciton generation (MEG) and exciton recombination were studied by femtosecond transient absorption spectroscopy in PbS nanoparticles (NPs) capped with oleic acid (PbS–OLA) and 2,3-dimercaptopropane sulfonate (PbS–DMPS) ligands. Analysis of the transient absorption data showed that the PbS–DMPS nanoparticles exhibit increased rates of multi- and single-exciton recombination compared with the PbS–OLA nanoparticles; however, the MEG yield for both sets of particles was the same within experimental error. The origin of the differences in the exciton recombination decay rates is unknown, but it is speculated that it may be due to the ionic functionality of DMPS or to the different ligating atoms of the OLA and DMPS ligands. The PbS–DMPS nanoparticles were highly sensitive to the presence of oxygen, which caused a dramatic increase in nonradiative decay pathways, which can be mistaken for multiexciton absorbance and decay. Removal of oxygen eliminated the nonradiative decay pathways. Overall, this study showed that the dynamics of MEG can be modified by changing the NP ligand shell, a result that may be useful in the development of NP-based thin-film solar devices.

A Study of Photoinduced Coherent Vibrations in Gold-Nanorod Dispersions

2020 ◽  
Vol 20 (7) ◽  
pp. 4557-4562
Author(s):  
Francesco Toschi ◽  
Daniele Catone ◽  
Lorenzo Di Mario ◽  
Patrick O’Keeffe ◽  
Alessandra Paladini ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Gold Nanorod ◽  
Transient Absorption Spectroscopy ◽  
Visible Range ◽  
Plasmonic Sensors ◽  
Femtosecond Transient Absorption ◽  
Highly Sensitive ◽  
Plasmon Resonances ◽  
Oscillation Frequencies ◽  
Transient Absorbance

Upon photoexcitation with a femtosecond laser pulse, the plasmonic resonance of a nanorod can couple with coherent vibrational modes generating a regular oscillating pattern in the transient absorbance of the nanostructure. The dynamics of the plasmon resonances of these materials are probed through femtosecond transient absorption spectroscopy in the spectral region between 400 nm and 1600 nm. Whereas in the visible range the spectra are comparable with the findings reported in the literature, the analysis of the transient NIR spectra revealed that their oscillation frequencies vary with wavelength, resulting in a strong distortion of the transient features that can be related to the specific lengths distribution of the nanorods contained in the sample. These findings suggest that in the design of efficient and highly sensitive gold-nanorod based plasmonic sensors a narrow size distribution of nanostructures is required.

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...

scholarly journals SnSe Nanosheets: From Facile Synthesis to Applications in Broadband Photodetections

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 49
Author(s):  
Xiangyang Li ◽  
Zongpeng Song ◽  
Huancheng Zhao ◽  
Wenfei Zhang ◽  
Zhenhua Sun ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Ultrafast Optics ◽  
Light Response ◽  
Transient Absorption Spectroscopy ◽  
Monolayer Graphene ◽  
Proof Of Concept ◽  
Facile Synthesis ◽  
Femtosecond Transient Absorption ◽  
Potential Applications ◽  
Promising Area

In recent years, using two-dimensional (2D) materials to realize broadband photodetection has become a promising area in optoelectronic devices. Here, we successfully synthesized SnSe nanosheets (NSs) by a facile tip ultra-sonication method in water-ethanol solvent which was eco-friendly. The carrier dynamics of SnSe NSs was systematically investigated via a femtosecond transient absorption spectroscopy in the visible wavelength regime and three decay components were clarified with delay time of τ1 = 0.77 ps, τ2 = 8.3 ps, and τ3 = 316.5 ps, respectively, indicating their potential applications in ultrafast optics and optoelectronics. As a proof-of-concept, the photodetectors, which integrated SnSe NSs with monolayer graphene, show high photoresponsivities and excellent response speeds for different incident lasers. The maximum photo-responsivities for 405, 532, and 785 nm were 1.75 × 104 A/W, 4.63 × 103 A/W, and 1.52 × 103 A/W, respectively. The photoresponse times were ~22.6 ms, 11.6 ms, and 9.7 ms. This behavior was due to the broadband light response of SnSe NSs and fast transportation of photocarriers between the monolayer graphene and SnSe NSs.

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