Optically transparent and electrically conductive oxide (TCO) semiconductor materials have long been considered as promising functional materials in applications such as flat panel displays, thin film solar cells and laser and light emitting diodes, due to their distinctive combination of optical transparency in the visible spectrum and high electrical conductivity.
TCO semiconductor materials are typically binary or ternary compounds containing one or two metallic elements. Most representative examples of TCO semiconductor materials are impurity-doped ZnO, In2O3, SnO2 and CdO as well as ternary compounds such as Zn2SnO4, ZnSnO3, Zn2In2O5, Zn3In2O6, In2SnO4, CdSnO3 and multi-component oxides consisting of combinations of ZnO, In2O3 and SnO2.
At present, Sn-doped In2O3 (ITO) is the most-widely employed material for TCO applications. However, large-scale implementation of ITO is severely hampered due to the scarcity, toxicity and high cost of Indium.
Alternative TCO materials with comparable device performance to that of ITO are therefore highly desired.
Several methods have been developed for manufacturing TCO thin films on various substrates, typically on glass substrates, including chemical vapour deposition, physical vapour deposition, pulsed laser deposition and magnetron sputtering.
These methods typically require high annealing temperature post-treatment steps, usually above 400° C., in order to improve the film crystallinity of the as-deposited TCO materials. The improved film crystallinity advantageously results in better optical transmittance, electrical conductivity and carrier mobility.
However, because conventional substrates cannot withstand high annealing temperatures, the deposition process must be completed under relatively low temperatures.
It is thus still needed in the art to provide for an alternative process for easily manufacturing optically transparent and electrically conducting assemblies on a variety of substrates including polymeric substrates and for assemblies endowed with high transparency and high electrical conductivity properties homogeneously over their surfaces, especially over large area surfaces.