Tuesday, August 6, 2013

1308.0770 (Kazuhiko Seki et al.)

Influence of Energetic Disorder on the Open-circuit Voltage in Organic
Bulkheterojunction Composites

Kazuhiko Seki, Kazuhiro Marumoto, M. Tachiya
Under open-circuit condition, the current is not extracted and the photogenerated carriers in principle disappear only by recombination. We study the open-circuit voltage, VOC, and transient photovoltage under the influence of bulk recombination in a medium with energetic disorder by using the multiple trapping (MT) model. The key parameter in the MT model is the dispersion parameter, {\alpha}, given by the ratio of thermal energy to the characteristic energy of trap states. We show that VOC depends linearly on the logarithm of the light intensity and the slope depends on {\alpha} of the MT model. Under the continuous irradiation of light, photovoltage response to the weak perturbation by a pulsed light obeys pseudofirst-order decay. The rate as a function of VOC is independent of the dispersion parameter. While, the rate obeys power law as a function of the light intensity and the exponent is given by 1/(1 + {\alpha}), which reduces to 1/2 in the absence of energetic disorder.
View original: http://arxiv.org/abs/1308.0770

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