Solution-processable and photopolymerisable TiO2 nanorods as dielectric layers for thin film transistors

We report the fabrication of a solution-processed n-type Thin Film Transistor (TFT) with current on/off ratios of 10⁴, a turn-on voltage (V_ON) of 1.2 V and a threshold voltage (V_T) of 6.2 V. The TFT incorporates an insoluble and intractable dielectric layer (k = 7–9) prepared in situ from solution-processed and then photopolymerised ligand-stabilised, inorganic/organic TiO₂ nanorods. A solution processed zinc oxide (ZnO) layer acts as the semiconductor. The new surface-modified TiO₂ nanorods were synthesised using a ligand replacement process with a monolayer coating of photopolymerisable 10-undecynylphosphonic acid (10UCYPA) to render them both soluble in common organic solvents and be photopolymerisable using UV-illumination after having been deposited on substrate surfaces from solution and drying.

A prototype solution-processed n-type thin film transistor was fabricated. The film incorporates a dielectric layer prepared from solution-processed and photopolymerised inorganic/organic TiO₂ nanorods and zinc oxide as the semiconductor, also deposited from solution.