Exciton regeneration at polymeric semiconductor heterojunctions

Control of the band-edge offsets at heterojunctions between organic semiconductors allows efficient operation of either photovoltaic or light-emitting diodes. We investigate systems where the exciton is marginally stable against charge separation and show via E-field-dependent time-resolved photolum...

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Bibliographic Details
Published in:Physical review letters 2004-06, Vol.92 (24), p.247402.1-247402.4, Article 247402
Main Authors: MORTEANI, Arne C, SREEARUNOTHAI, Paiboon, HERZ, Laura M, FRIEND, Richard H, SILVA, Carlos
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Electron states
Exact sciences and technology
Excitons and related phenomena
Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation
Photoluminescence
Physics
Solid organic materials
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Summary:Control of the band-edge offsets at heterojunctions between organic semiconductors allows efficient operation of either photovoltaic or light-emitting diodes. We investigate systems where the exciton is marginally stable against charge separation and show via E-field-dependent time-resolved photoluminescence spectroscopy that excitons that have undergone charge separation at a heterojunction can be efficiently regenerated. This is because the charge transfer produces a geminate electron-hole pair (separation 2.2-3.1 nm) which may collapse into an exciplex and then endothermically (E(A)=100-200 meV) back transfer towards the exciton.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.92.247402