Investigation on electrohydrodynamic printing of conductors in display backplane circuits

Abstract

Large-area display panels encounter voltage drops across the panel, which causes nonuniform light emission of their pixels. Such a voltage drop is due to the high sheet resistance of the transparent conductive electrode. A remedy to overcome the problem is to add assistive conductors between pixels so that the cross-panel resistance can be reduced. Electrohydrodynamic jet (EHJ) printing of silver ink has been investigated for its suitability to fabricate the assistive conductors. It was found that the high electric field in the EHJ printer could influence the characteristics of thin-film transistors (TFTs) of the backplane circuit, causing noticeable shifts in the threshold voltage due to the field-induced charge accumulation in the TFT semiconductor channel. A modified version of TFT was proposed and the influence of the electric field on the TFTs was greatly reduced.