Highly Transparent Gallium-Doped Zinc Oxide Nanosheets Enabling Stable All-in-One Red-Green-Blue Photodetectors with High Responsivity

Two-dimensional zinc oxide nanosheets are attractive building blocks for ultrathin optoelectronic devices because of their high optical transparency and chemical stability; yet their weak visible-light response has hindered practical applications. Here, we demonstrate gallium-doped zinc oxide nanosheets as highly transparent and thermally robust platforms for all-in-one red-green-blue photodetectors. Gallium-doped nanosheets are synthesized via ionic layer epitaxy with precise compositional control. Structural, optical, and electrical analyses reveal that gallium doping concurrently enhances multiple properties, leading to improved photodevice performance. Gallium-doped zinc oxide nanosheets exhibit responsivities of up to 800 A W–1, carrier mobilities of 1.94 cm2 V–1s–1, and an average visible transmittance of 99.995% per nanosheet, enabling broadband photodetection without sacrificing optical throughput. Owing to their solution processability, the nanosheets can be vertically assembled into Bayer-like stacked architectures that decode red, green, and blue signals within a single pixel. Notably, the stacked photodetectors maintain stable photoresponse and excellent thermal and oxidative stability up to 450 °C, highlighting their promise for high-density, ultracompact color imaging technologies.