Mode-selective vibrational modulation of charge transport in organic electronic devices.
Nat Commun 2015;
6:7880. [PMID:
26246039 PMCID:
PMC4538862 DOI:
10.1038/ncomms8880]
[Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 06/23/2015] [Indexed: 11/25/2022] Open
Abstract
The soft character of organic materials leads to strong coupling between molecular, nuclear and electronic dynamics. This coupling opens the way to influence charge transport in organic electronic devices by exciting molecular vibrational motions. However, despite encouraging theoretical predictions, experimental realization of such approach has remained elusive. Here we demonstrate experimentally that photoconductivity in a model organic optoelectronic device can be modulated by the selective excitation of molecular vibrations. Using an ultrafast infrared laser source to create a coherent superposition of vibrational motions in a pentacene/C60 photoresistor, we observe that excitation of certain modes in the 1,500–1,700 cm−1 region leads to photocurrent enhancement. Excited vibrations affect predominantly trapped carriers. The effect depends on the nature of the vibration and its mode-specific character can be well described by the vibrational modulation of intermolecular electronic couplings. This presents a new tool for studying electron–phonon coupling and charge dynamics in (bio)molecular materials.
The electronic properties of organic molecules are sensitive to structural dynamics, but device control through this phenomenon has not been attained. Bakulin et al. show that the photoconductivity can be modulated by selective excitation of molecular vibrations in an organic optoelectronic device.
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