Advanced IGZO Phototransistor Arrays: Enhancing Visible Light Detection Through Selectively Electrohydrodynamic Jet‐Printed Photocatalytic Layer Formation

Abstract Exploring new horizons in phototransistors with an emphasis on mass customization is essential. Herein, a method for enhancing the performance of indium‐gallium‐zinc‐oxide (IGZO) phototransistors by incorporating a selectively formed tungsten trioxide (WO 3 ) photocatalytic layer, utilizing electrohydrodynamic (EHD) jet‐printing is proposed. This approach aims to achieve significant manufacturing advantages and enhance functionality. An oxidizing solution of hydrogen peroxide (H 2 O 2 ) doped with hydroxyethyl cellulose (HEC) is introduced to selectively oxidize tungsten (W) electrodes. In this mixture, H 2 O 2 is responsible for the selective oxidation of W, whereas HEC contributes to the viscosity regulation and the formation of subgap states. The resulting selectively oxidized photocatalytic layer significantly expands its visible light absorption capacity to red light. Therefore, the optimized device, particularly under red light (635 nm) 5 mW mm −2 , shows a remarkable enhancement in its optoelectronic characteristic: photoresponsivity increases from 29.71 to 124.54 A W −1 , photosensitivity from 1.99 × 10 ‐1 to 1.79 × 10 4 , and detectivity from 1.31 × 10 7 to 1.98 × 10 8 Jones compared to IGZO phototransistors without selectively oxidized photocatalytic layer. This advancement not only enhances the visible light detection capacity but also minimizes the persistent photoconductance issue inherent in IGZO devices. The demonstration of 6 × 6 phototransistor array illustrates the potential for image sensor applications, showcasing the practicality of mass customization.