Hybrid Phototransistors-based on Dye-functionalised ZnO Semiconducting Channels

Pattanasattayavong, P and Thomas, Stuart and Adamopoulos, George and Labram, John and Anthopoulos, Thomas (2011) Hybrid Phototransistors-based on Dye-functionalised ZnO Semiconducting Channels. In: MRS 2011 Spring Meeting, 2011-04-26.

Abstract

Oxide semiconductors are a promising family of materials for applications in transparent thin-film transistors for large area electronics. As a result research effort in recent years has been mainly focussing on the development of improved oxide semiconductors and devices with enhanced carrier mobility and operating stability. Here we report on the use of solution processed oxide semiconductors and organic light-absorbing dyes for the demonstration of novel bifunctional hybrid transistors. Specifically, we combine solution processed ZnO with light absorbing organic dyes, containing suitable anchoring groups, to produce photo-active ZnO-dye interfaces and implement these into optimised transistor architectures. Despite the incorporation of the organic dye on the surface of the ZnO channel layer, the transistors exhibit good operating characteristics with high electron mobility and excellent current on/off ratio. In addition to their electrical switching, the hybrid transistors are also found to exhibit high photoresponse to visible light. In particular, the channel current in these devices can easily be modulated by either the illumination intensity of the incident light and/or its wavelength. To the best of our knowledge, this is the first ever demonstration of a hybrid phototransistor based on a combination of oxide and organic materials. Use of such devices could one day provide significant advantages over conventional diode-type photodetectors due to the high internal signal gain, the intrinsically low RC constants (important for high-speed applications) and the potential for colour selective light detection by chemical tailoring of the organic dye. Apart from their technological applications, such hybrid photoactive devices could also provide an ideal test-bed for the study of the charge transfer processes at oxide/organic interfaces upon electrical/photo-excitation.