Optical properties of a-Si:H thin-film transistors by illumination by white light with different colour temperatures

This work investigates the optical properties of hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) using the transmittances of colour filters and the spectra of commercialised white light-emitting diodes (LEDs). The ratios of the measured photocurrents obtained using the TFTs that are covered and are not covered colour filters are related to the effective illumination from white LEDs with different colour temperatures that pass through the colour filters. A new factor that is based on these ratios of photocurrents is proposed to evaluate the output characteristics of optical sensors with our previously developed white-light photocurrent gating (WPCG) structure. The analytical results demonstrate that the proposed factor and the output voltages of the WPCG structure are highly correlated with each other, favouring the optimisation of the design parameters to realise an optical sensor that is highly reliable under diverse conditions for use in large interactive displays.