Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 44: Organic semiconductors I

HL 44.5: Talk

Thursday, March 26, 2009, 12:00–12:15, POT 51

The impact of oxygen on trap states in P3HT:PCBM blends — •Julia Schafferhans¹, Roland Marx¹, Carsten Deibel¹, and Vladimir Dyakonov^1,2 — ¹Julius-Maximilians-University of Würzburg, Institute of Physics, Experimental Physics VI, D-97074 Würzburg — ²Bavarian Centre for Applied Energy Research e.V. (ZAE Bayern), D-97074 Würzburg

Conjugated polymers receive a growing interest for application in organic solar cells due to their low cost processability from solution. Efficiencies of almost 6% for organic solar cells have already been achieved. A limiting factor, so far, is the lifetime of these devices. To investigate the stability and to obtain an understanding of the underlying degradation mechanism is an important prerequisite for a stable performance. Accordingly, the presence of defect states can be critical, as they reduce the charge carrier mobility, affect the driving voltage, disturb the internal field distribution and can act as recombination centers. We present investigations on the influence of oxygen on defect states in P3HT:PCBM blends, one of the most promising candidates for organic solar cells, by applying the thermally stimulated current technique. The results for the blends are compared with these obtained for pristine P3HT samples. The influence of the trap states on the charge carrier mobility as well as the reversibility of the oxygen-induced degradation are discussed.