Imperial College London

ProfessorMartinHeeney

Faculty of Natural SciencesDepartment of Chemistry

Professor of Organic Materials
 
 
 
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Contact

 

+44 (0)20 7594 1248m.heeney Website

 
 
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Location

 

401GMolecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Citation

BibTex format

@article{Eisner:2019:10.1021/jacs.9b01465,
author = {Eisner, FD and Azzouzi, M and Fei, Z and Hou, X and Anthopoulos, TD and Dennis, TJS and Heeney, M and Nelson, J},
doi = {10.1021/jacs.9b01465},
journal = {J Am Chem Soc},
title = {Hybridization of Local Exciton and Charge-Transfer States Reduces Nonradiative Voltage Losses in Organic Solar Cells.},
url = {http://dx.doi.org/10.1021/jacs.9b01465},
year = {2019}
}

RIS format (EndNote, RefMan)

TY  - JOUR
AB - A number of recent studies have shown that the nonradiative voltage losses in organic solar cells can be suppressed in systems with low energetic offsets between donor and acceptor molecular states, but the physical reasons underpinning this remain unclear. Here, we present a systematic study of 18 different donor/acceptor blends to determine the effect that energetic offset has on both radiative and nonradiative recombination of the charge-transfer (CT) state. We find that, for certain blends, low offsets result in hybridization between charge-transfer and lowest donor or acceptor exciton states, which leads to a strong suppression in the nonradiative voltage loss to values as low as 0.23 V associated with an increase in the luminescence of the CT state. Further, we extend a two-state CT-state recombination model to include the interaction between CT and first excited states, which allows us to explain the low nonradiative voltage losses as an increase in the effective CT to ground state oscillator strength due to the intensity borrowing mechanism. We show that low nonradiative voltage losses can be achieved in material combinations with a strong electronic coupling between CT and first excited states and where the lower band gap material has a high oscillator strength for transitions from the excited state to the ground state. Finally, from our model we propose that achieving very low nonradiative voltage losses may come at a cost of higher overall recombination rates, which may help to explain the generally lower FF and EQE of highly hybridized systems.
AU - Eisner,FD
AU - Azzouzi,M
AU - Fei,Z
AU - Hou,X
AU - Anthopoulos,TD
AU - Dennis,TJS
AU - Heeney,M
AU - Nelson,J
DO - 10.1021/jacs.9b01465
PY - 2019///
TI - Hybridization of Local Exciton and Charge-Transfer States Reduces Nonradiative Voltage Losses in Organic Solar Cells.
T2 - J Am Chem Soc
UR - http://dx.doi.org/10.1021/jacs.9b01465
UR - https://www.ncbi.nlm.nih.gov/pubmed/30882218
ER -