Berlin 2005 – scientific programme

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HL: Halbleiterphysik

HL 61: Organische Halbleiter

HL 61.9: Talk

Wednesday, March 9, 2005, 12:45–13:00, TU P270

COMPARATIVE ELECTROABSORPTION STUDIES ON ORGANIC SEMICONDUCTOR DEVICES WITH VARIOUS INTERFACIAL LAYERS — •Christoph Lungenschmied¹, Markus Scharber², Helmut Neugebauer¹, and Serdar Sariciftci¹ — ¹Linz Institute for Organic Solar Cells (LIOS), Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria — ²Konarka Austria, Gruberstr. 40-42, 4020 Linz, Austria

Electroabsorption spectroscopy in reflection geometry was used to probe the electric field induced changes in the transmission of thin organic semiconducting films sandwiched between asymmetric contacts. The photoactive layer of the investigated devices consisted of a soluble polyphenylene vinylene derivative, namely MDMO-PPV, spin cast on ITO coated glass substrates and covered with an Al layer as top electrode. The change in the transmission (ΔT) due to the Stark effect was monitored using a modulation technique at various applied DC voltages (VDC). It is observed, that ∣ Δ T ∣ goes to zero at positive VDC (ITO is +), indicating that the internal electric field is cancelled by the externally applied field.
This VDC was found to change by introducing interfacial layers. When using the same device setups in photovoltaic studies the maximum open circuit voltage (VOC) qualitatively follows the same trend. A possible correlation of the internal electric field with photovoltaic device parameters will be described.