Dresden 2014 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 61: Organic electronics and photovoltaics III (organized by CPP)

HL 61.8: Talk

Wednesday, April 2, 2014, 11:30–11:45, ZEU 260

Intrinsic charge carrier mobility in PCDTBT:PC₇₁BM blend thin films investigated by simultaneous transient absorption and transient microwave conductivity measurements — •Andreas Fritze¹, Jeremias Weinrich¹, Vladimir Dyakonov^1,2, and Carsten Deibel¹ — ¹Experimental Physics VI, Julius Maximilian University of Würzburg, 97074 Würzburg — ²ZAE Bayern, 97074 Würzburg

PCDTBT is a promising low-bandgap polymer for photovoltaic applications that has demonstrated unique recombination dynamics compared to the model P3HT system. Usually, the recombination dynamics in organics blends is expected to be proportional to the macroscopic charge carrier mobility, which is influenced by trapping and therefore potentially depends on the charge carrier concentration. For PCDTBT blends, we want to determine if the recombination dynamics are indeed governed exclusively by the low macroscopic mobility or if it is dominated by the, high local mobility. Therefor, we performed simultaneous measurements of transient absorption (TAS) and transient microwave conductivity on PCDTBT:PC₇₁BM thin films on a 10 ns to 1 ms time scale. TAS probes the charge carrier density, whereas the microwave experiment is sensitive to the intrinsic, high frequency conductivity. By investigating the charge carrier dynamics and conductivity at different laser pump intensities and temperatures, we can separate the effects of mobility relaxation from carrier concentration dependent mobility in order to understand the dominant loss mechanism in organic solar cells.