Multi-photoactive quantum-dot channels for zinc oxide phototransistors by a surface-engineering patterning process

Abstract

Red, green, blue (RGB) selective zinc oxide (ZnO) phototransistors with multi-photoactive quantum-dot (QD) channels have been fabricated by a charge-assisted layer-by-layer (LbL) patterning process. QDs were patterned as RGB pixels in multi-photoactive QD channels through the LbL process. The solution-processed ZnO film, which acts as an active-channel layer of the ZnO TFTs, is patterned via a photoinduced surface engineering method to reduce the leakage current of the ZnO TFTs. The average off-current of the patterned ZnO TFTs reduced from 10(-10) to 10(-11) A. QDs absorb visible light and generate photoelectrons, which are then transferred to the ZnO to produce photocurrents. The device shows photoresponsivity of 9.4 mA/W, 12.5, and 137 A/W to the illumination of 638, 520, and 405 nm wavelength light. Our results suggest a promising way to develop an RGB selective phototransistor that uses QDs as a visible light absorption layer and ZnO as an active channel semiconductor.