Evidence for Excimer Photoexcitations in an Ordered π-Conjugated Polymer Film

Abstract

We report pressure-dependent transient picosecond and continuous-wave photomodulation studies of disordered and ordered films of 2-methoxy-5-(2-ethylhexyloxy) poly(para-phenylenevinylene). Photoinduced absorption (PA) bands in the disordered film exhibit very weak pressure dependence and are assigned to intrachain excitons and polarons. In contrast, the ordered film exhibits two additional transient PA bands in the midinfrared that blueshift dramatically with pressure. Based on high-order configuration interaction calculations we ascribe the PA bands in the ordered film to excimers. Our work brings insight to the exciton binding energy in ordered films versus disordered films and solutions. The reduced exciton binding energy in ordered films is due to new energy states appearing below the continuum band threshold of the single strand.

5.5 pages, 5 figures

References in corpus (5)

• The role of intermolecular coupling in the photophysics of disordered organic semiconductors: Aggregate emission in regioregular polythiophene
• Theory of interfacial charge-transfer complex photophysics in $\pi$-conjugated polymer-fullerene blends
• Photophysics of charge-transfer excitons in thin films of π-conjugated polymers
• Metastable polaron supporting phase in poly-p-phenylene films induced by UV illumination
• Correlated-electron description of the photophysics of thin films of $\pi$-conjugated polymers

Cited by in corpus (3)

• Theory of Singlet Fission in Polyenes, Acene Crystals and Covalently Linked Acene Dimers
• Subgap Two-Photon States in Polycyclic Aromatic Hydrocarbons: Evidence for Strong Electron Correlations
• Does Singlet Fission Enhance the Performance of Organic Solar Cells?