Optical Gain in Semiconducting Polymer Nano and Mesoparticles

Mark Geoghegan (1) , Marta M Mróz (2) , Chiara Botta (3) , Laurie Parrenin (4) , Cyril Brochon (4) , Eric Cloutet (4) , Eleni Pavlopoulou (4) , Georges Hadziioannou (4) , Tersilla Virgili (2)

1 Department of Physics and Astronomy [Sheffield]
2 INFM-Dipartimento di Fisica-Politecnico di Milano
3 SCITEC - Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”
4 Team 4 LCPO : Polymer Materials for Electronic, Energy, Information and Communication Technologies

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. In the nanoparticle film, as for a uniform film of the pure polymer, charge formation is induced by UV excitation pump with a formation time of around 1 ps, 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. In the mesoparticle film, charge generation after UV excitation appears after around 50 ps, but little is observed after visible pump excitation. Optical gain in the mesoparticle films is observed after excitation at both 400 and 610 nm.

Mots clés: transient absorption spectroscopy; conjugated polymers; stimulated emission; nanoparticles; mesoparticles

Domaines: Polymères

Mark Geoghegan, Marta M Mróz, Chiara Botta, Laurie Parrenin, Cyril Brochon, et al.. Optical Gain in Semiconducting Polymer Nano and Mesoparticles. Molecules, 2021, 26 (4), pp.1138. ⟨10.3390/molecules26041138⟩. ⟨hal-03151861⟩