Dresden 2017 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 59: Focus: Static and Dynamic Disorder Phenomena on the Transport in Organic Semiconductors II

CPP 59.4: Talk

Thursday, March 23, 2017, 16:15–16:30, ZEU 222

Dispersive Charge Transport and Recombination in Polymer Solar Cells — •John Love and Dieter Neher — University of Potsdam

Charge transport in organic semiconductors has long been known as governed by hopping through a broad distribution of localized electronic states. Yet, the role of charge relaxation and dispersive charge transport in the steady state operation of organic solar cells, remains highly debated. Here we address this question, of how thermalization determines the dynamics of charge transport and non-geminate recombination, in the TQ1:PCBM system. Via time delayed collection field, a state-of-the-art dynamic charge extraction technique, we are able to experimentally follow the rate of recombination from nanoseconds to microseconds inside of a working device. We show that the recombination indeed shows a pronounced slowing over time, experimentally validating results of previously published Monte Carlo simulations.[1] The steady state recombination rate at open circuit voltage matches well with the nearly fully relaxed charges found at long time scales of the transient experiments suggesting that open circuit, it is relaxed carriers which undergo recombination.

[1] Melianas, A., Pranculis, V., Devizis, A., Gulbinas, V., Inganas, O. and Kemerink, M. (2014), Adv. Funct. Mater., 24: 4507.