Objective
This project involves the fabrication and characterisation of novel photoconductive devices formed by heterostructures of organic and inorganic materials. Organic materials that will be used are macrocyclic compounds of phthalocyanine (Pc) molecules, specially synthesised for Langmuir-Blodgett deposition and spin coating. Device structures are fabricated by depositing thin films of Pc molecules on n-type oxide semiconductors such as TiOX. The absorption in Pc molecules reaches its peak at a wavelength between 620nm to 720nm but a TiOX layer remains transparent at these wavelengths because of its larger intrinsic bandgap. Electron-hole pairs will be generated in Pc layers by photon excitation. Since electron affinity of a TiOX layer is higher than Pc films, electrons will be separated from holes and then transferred to the conduction band of the TiOX layer. With appropriate electrode configurations the TiOX layer will now act as a charge transport medium under the action of an electric field. Because of higher electron mobilities in inorganic semiconductors, it is expected to achieve enhanced photoconduction. Devices will be less noisy than existing photoconductors because there is conduction due to no minority carriers.
TiOX layers will be produced by sol-gel techniques; structural and electrical analysis will be performed. Fundamental and systematic investigations will be undertaken to study the interfaces, the mechanism of photogeneration and carrier transport to optimise the light-harvesting properties of the structures. Different device structures will be constructed and their characteristics evaluated for maximum efficiency.
Topic(s)
Call for proposal
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S1 1WB Sheffield
United Kingdom