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Exciton Regeneration at Polymeric Semiconductor Heterojunctions

Arne C. Morteani·Paiboon Sreearunothai·Laura M. Herz·Richard H. Friend·Carlos Silva
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Abstract

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 2.2-3.1nm) which may collapse into an exciplex and then endothermically (E=100-200meV) back-transfer towards the exciton.

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Arne C. Morteani, Paiboon Sreearunothai, Laura M. Herz, Richard H. Friend, Carlos Silva. 2004-04-08. Exciton Regeneration at Polymeric Semiconductor Heterojunctions. https://doi.org/10.1103/physrevlett.92.247402

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