Please use this identifier to cite or link to this item: http://dr.iiserpune.ac.in:8080/xmlui/handle/123456789/2228
Title: Origin of Unusual Excitonic Absorption and Emission from Colloidal Ag2S Nanocrystals: Ultrafast Photophysics and Solar Cell
Authors: MIR, WASIM J.
SWARNKAR, ABHISHEK
Sharma, Rituraj
Katti, Aditya
Adarsh, K. V.
NAG, ANGSHUMAN
Dept. of Chemistry
Keywords: Unusual Excitonic Absorption
Emission from Colloidal
Nanocrystals
Nanocrystals
Solar Cell
Monodisperse CdS NCs
2015
Issue Date: Oct-2015
Publisher: American Chemical Society
Citation: Journal of Physical Chemistry Letters, 6 (19), 3915-3922.
Abstract: Colloidal Ag2S nanocrystals (NCs) typically do not exhibit sharp excitonic absorption and emission. We first elucidate the reason behind this problem by preparing Ag2S NCs from nearly monodisperse CdS NCs employing cation exchange reaction. It was found that the defect-related midgap transitions overlap with excitonic transition, blurring the absorption spectrum. On the basis of this observation, we prepared nearly defect-free Ag2S NCs using molecular precursors. These defect-free Ag2S NCs exhibit sharp excitonic absorption, emission (quantum yield 20%) in near-infrared (853 nm) region, and improved performance of Ag2S quantum-dot-sensitized solar cells (QDSSCs). Samples with lower defects exhibit photoconversion efficiencies >1% and open circuit voltage of ∼0.3 V, which are better compared with prior reports of Ag2S QDSSCs. Femtosecond transient absorption shows pump–probe two-photon absorption above 630 nm and slow-decaying excited state absorption below 600 nm. Concomitantly, open-aperture z-scan shows strong two-photon absorption at 532 nm (coefficient 55 ± 3 cm/GW).
URI: http://dr.iiserpune.ac.in:8080/xmlui/handle/123456789/2228
https://doi.org/10.1021/acs.jpclett.5b01692
ISSN: 1948-7185
Appears in Collections:JOURNAL ARTICLES

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