Contact properties of PEDOT:PSS

With ongoing rapid development of printed and organic electronics, high attention is paid to studies of contact resistance, which is recognized as the crucial factor affecting the overall performance of devices based on organic semiconductors. This paper presents the combined analysis of contact resistance in metal-organic heterostructures based on simultaneous employment of both the conventional and the modified transfer length method (C-TLM, M-TLM). Three modifications of the PEDOT:PSS with composition ratios 5:10, 3:10 and 2:10 between PEDOT and PSS in the final polyelectrolytic dispersions were chosen as the model organic semiconductor materials. Their contact properties were investigated at junctions with Au plated copper electrodes. The test vehicles consisted of PEDOT:PSS deposited by dip coating on glass-epoxy substrates with collinear electrodes with distances scaled from 100 μm to 1000 μm. Total resistances derived from I-V measurement on each electrode pair taken in relation to their distances were subjected to TLM analysis with linear regression fitting giving the information of contact and sheet resistance. The most consistent results were obtained for the PEDOT:PSS (5:10) and confirmed substantial contribution of the contact resistance, which constitutes up to 83 % of the overall electrical resistance of tested structures in the case of the shortest electrode distance.