Regensburg 2004 – scientific programme

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SYOH: Organic and Hybrid Systems for Future Electronics

SYOH 5: Poster

SYOH 5.70: Poster

Thursday, March 11, 2004, 18:00–21:00, B

Effect of Annealing on Characteristic Hole Traps in Poly(3hexyl-thiophene) Thin Films — •Zivayi Chiguvare, Jürgen Parisi, and Vladimir Dyakonov — University of Oldenburg, Faculty of Physics (EHF), 26111 Oldenburg

Bulk transport properties of poly(3hexylthiophene) (P3HT) were studied by analysing temperature dependent current-voltage characteristics of the polymer thin films sandwiched between ITO/PEDOT and aluminium electrodes. It was found that the contacts limit charge injection under reverse bias, but under forward bias the current is limited by space charge that accumulates near the hole injecting electrode (ITO/PEDOT) due to the poor transport properties of P3HT. The forward current density obeys a power law of the form J∼ V^m, characteristic of SCLC in the presence of exponentially distributed traps within the band gap. The energy that characterises the exponential distribution of hole traps increases with temperature. Hole trap density was found to decrease on annealing the devices, resulting in more than 2 orders of magnitude increase in SCLC hole mobility. We attribute this to better chain packing and thus a large increase in the degree of interchain interactions as compared to as-cast films.