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.
@article{arxiv.cond-mat/0404209,
title = {Exciton Regeneration at Polymeric Semiconductor Heterojunctions},
author = {Arne C. Morteani and Paiboon Sreearunothai and Laura M. Herz and Richard H. Friend and Carlos Silva},
journal= {arXiv preprint arXiv:cond-mat/0404209},
year = {2013}
}
Comments
10 pages, 4 figures. Manuscript in press in Phys. Rev. Lett