Confocal ultrafast pump-probe spectroscopy: A new technique to explore nanoscale composites

Tersilla Virgili*, Giulia Grancini, Egle Molotokaite, Inma Suarez-Lopez, Sai Kiran Rajendran, Andrea Liscio, Vincenzo Palermo, Guglielmo Lanzani, Dario Polli, Giulio Cerullo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

This article is devoted to the exploration of the benefits of a new ultrafast confocal pump-probe technique, able to study the photophysics of different structured materials with nanoscale resolution. This tool offers many advantages over standard stationary microscopy techniques because it directly interrogates excited state dynamics in molecules, providing access to both radiative and non-radiative deactivation processes at a local scale. In this paper we present a few different examples of its application to organic semiconductor systems. The first two are focussed on the study of the photophysics of phase-separated polymer blends: (i) a blue-emitting polyfluorene (PFO) in an inert matrix of PMMA and (ii) an electron donor polythiophene (P3HT) mixed with an electron acceptor fullerene derivative (PCBM). The experimental results on these samples demonstrate the capability of the technique to unveil peculiar interfacial dynamics at the border region between phase-segregated domains, which would be otherwise averaged out using conventional pump-probe spectroscopy. The third example is the study of the photophysics of isolated mesoscopic crystals of the PCBM molecule. Our ultrafast microscope could evidence the presence of two distinctive regions within the crystals. In particular, we could pinpoint for the first time areas within the crystals showing photobleaching/stimulated emission signals from a charge-transfer state.

Original languageEnglish
Pages (from-to)2219-2226
Number of pages8
JournalNanoscale
Volume4
Issue number7
DOIs
Publication statusPublished - 7 Apr 2012

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