Optical Gain in Semiconducting Polymer Nano and Mesoparticles

Autor: Mark Geoghegan, Marta M. Mróz, Chiara Botta, Laurie Parrenin, Cyril Brochon, Eric Cloutet, Eleni Pavlopoulou, Georges Hadziioannou, Tersilla Virgili
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Molecules, Vol 26, Iss 4, p 1138 (2021)
Druh dokumentu: article
ISSN: 26041138
1420-3049
DOI: 10.3390/molecules26041138
Popis: The presence of excited-states and charge-separated species was identified through UV and visible laser pump and visible/near-infrared probe femtosecond transient absorption spectroscopy in spin coated films of poly[N-9″-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) nanoparticles and mesoparticles. Optical gain in the mesoparticle films is observed after excitation at both 400 and 610 nm. In the mesoparticle film, charge generation after UV excitation appears after around 50 ps, but little is observed after visible pump excitation. In the nanoparticle film, as for a uniform film of the pure polymer, charge formation was efficiently induced by UV excitation pump, while excitation of the low energetic absorption states (at 610 nm) induces in the nanoparticle film a large optical gain region reducing the charge formation efficiency. It is proposed that the different intermolecular interactions and molecular order within the nanoparticles and mesoparticles are responsible for their markedly different photophysical behavior. These results therefore demonstrate the possibility of a hitherto unexplored route to stimulated emission in a conjugated polymer that has relatively undemanding film preparation requirements.
Databáze: Directory of Open Access Journals
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