Topic
Exciton
About: Exciton is a research topic. Over the lifetime, 31603 publications have been published within this topic receiving 810642 citations.
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TL;DR: The observation of a photoinduced absorption band strictly correlated to the photobleaching of the EX1 transition supports the excitonic model for primary excitations in SWNTs.
Abstract: We study exciton (EX) dynamics in single-walled carbon nanotubes (SWNTs) included in polymethylmethacrylate by two-color pump-probe experiments with unprecedented temporal resolution. In the semiconducting SWNTs, we resolve the intersubband energy relaxation from the EX2 to the EX1 transition and find time constants of about 40 fs. The observation of a photoinduced absorption band strictly correlated to the photobleaching of the EX1 transition supports the excitonic model for primary excitations in SWNTs. We also detect in the time domain coherent oscillations due to the radial breathing modes at $\ensuremath{\approx}250\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}1}$.
184 citations
TL;DR: The results suggest that low PL QYs of SWNTs are due to the combination of high-diffusive exciton mobility with the presence of only a few quenching sites.
Abstract: Photoluminescence quantum yields and nonradiative decay of the excitonic S(1) state in length fractionated (6,5) single-wall carbon nanotubes (SWNTs) are studied by continuous wave and time-resolved fluorescence spectroscopy. The experimental data are modeled by diffusion limited contact quenching of excitons at stationary quenching sites including tube ends. A combined analysis of the time-resolved photoluminescence decay and the length dependence of photoluminescence quantum yields (PL QYs) from SWNTs in sodium cholate suspensions allows to determine the exciton diffusion coefficient D = 10.7 ± 0.4 cm(2)s(-1) and lifetime τ(PL) for long tubes of 20 ± 1 ps. PL quantum yields Φ(PL) are found to scale with the inverse diffusion coefficient and the square of the mean quenching site distance, here l(d) = 120 ± 25 nm. The results suggest that low PL QYs of SWNTs are due to the combination of high-diffusive exciton mobility with the presence of only a few quenching sites.
183 citations
TL;DR: In this article, a combination of optimized AIN buffer layers and a two-step growth process leads to GaN layers of high crystal quality (8 arcmin X-ray diffraction full-width at half-maximum) and flat surfaces (57 A rms).
183 citations
TL;DR: In this article, the exciton binding energy in perovskite semiconductor CsSnI3 was determined through a series of steady state and time-resolved photoluminescence measurements in a temperature range of 10-300 K.
183 citations
TL;DR: In this article, optical absorption and electro absorption studies on the lead-iodide-based natural quantum-well perovskite-type crystals with different well width (C6H13NH3)2(CH3NH3),m−1PbmI3m+1 with decreasing well thickness, m, the resonance energies of the lowest energy excitons shift to higher energy due to the increase of the bandgap.
183 citations