Optical spectroscopy of organic semiconductor monolayers

Rui He, Nancy G. Tassi, Graciela B. Blanchet, Aron Pinczuk

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Growing interest in organic molecular semiconductors is stimulated by their promising applications in flexible devices. Pentacene is a benchmark organic semiconductor material because of its potential applications in high mobility thin film transistors and optoelectronic devices. Highly uniform monolayers of pentacene grown on polymeric substrate of poly alpha-methylstyrene exhibit sharp and intense free exciton (FE) luminescence at low temperatures. The FE emission displays characteristic intensity that grows quadratically with the number of layers. Large enhancements of Raman scattering intensities at the FE resonance enable the first observations of low-lying lattice vibrational modes in films reaching the single monolayer level. The low-lying modes exhibit characteristic changes when going from a single monolayer to two layers, revealing that a phase akin to a thin film phase of pentacene already emerges in structures of only two monolayers. A simple analysis of mode splittings offers estimates of the strength of inter-layer interactions. The results demonstrate novel venues for ultra-thin film characterization and studies of interface effects in organic molecular semiconductor structures.

Original languageEnglish
Title of host publicationSeventh International Conference on Thin Film Physics and Applications
StatePublished - 2011
Event7th International Conference on Thin Film Physics and Applications - Shanghai, China
Duration: Sep 24 2010Sep 27 2010

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


Conference7th International Conference on Thin Film Physics and Applications


  • Luminescence
  • Monolayer
  • Pentacene
  • Raman scattering


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