Volume 216, 2019

How charges separate: correlating disorder, free energy, and open-circuit voltage in organic photovoltaics

Abstract

In order for a photovoltaic cell to function, charge carriers produced by photoexcitation must fully dissociate and overcome their mutual Coulomb attraction to form free polarons. This becomes problematic in organic systems in which the low dielectric constant of the material portends a long separation distance between independent polaron pairs. In this paper, we discuss our recent efforts to correlate the role of density of states, entropy, and configurational and energetic disorder to the open-circuit voltage, VOC, of model type-II organic polymer photovoltaics. By comparing the results of a fully interacting lattice model to those predicted by a Wigner–Weisskopf type model we find that energetic disorder does play a significant role in determining the VOC; however, mobility perpendicular to the interface plays the deciding role in the eventual fate of a charge-separated pair.

Graphical abstract: How charges separate: correlating disorder, free energy, and open-circuit voltage in organic photovoltaics

Associated articles

Article information

Article type
Paper
Submitted
19 nóv. 2018
Accepted
22 jan. 2019
First published
22 jan. 2019

Faraday Discuss., 2019,216, 236-251

Author version available

How charges separate: correlating disorder, free energy, and open-circuit voltage in organic photovoltaics

D. P. Mroczek, V. Lankevich and E. R. Bittner, Faraday Discuss., 2019, 216, 236 DOI: 10.1039/C8FD00182K

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