Smartphone cameras could get dramatically smaller without losing image quality, according to research published in the journal ACS Nano. Researchers at Nagoya University in Japan have developed ultrathin gallium-doped zinc oxide nanosheets that allow a single pixel to detect red, green, and blue light at the same time, something conventional camera sensors cannot do.
Most commercial cameras use what is called a Bayer array, a checkerboard arrangement of color filters spread across millions of pixels. Each pixel in that system captures only one color. The camera's processor then reconstructs a full-color image by pulling data from neighboring pixels. If a single pixel could detect all three colors simultaneously, the total number of pixels needed could be cut by as much as 75 percent, shrinking the sensor while keeping image resolution the same.
As reported by Phys.org, transparent nanosheets make this possible because light passes through them. That allows multiple layers to be stacked on top of each other, with each layer detecting a different part of the color spectrum. The approach also removes several complex steps from the manufacturing process used in conventional sensors, which could lower production costs.
The research team, led by Professor Minoru Osada along with researchers Ruben Canton-Vitoria and Vivid Meelab at Nagoya University's Institute of Materials and Systems for Sustainability, started with zinc oxide nanosheets. Zinc oxide is highly transparent and chemically stable, but early tests revealed a serious problem: the nanosheets responded too weakly to visible light to be useful in a camera sensor.
To fix that, the team altered the electronic structure of the zinc oxide by adding gallium. That modification created what are called trap states, which capture electrons and convert incoming light into electrical signals. The result was a material that responded strongly to visible light while still remaining nearly transparent.
The performance numbers were striking. Each layer of the gallium-doped zinc oxide transmits 99.995 percent of visible light, converting just 0.005 percent of absorbed light energy into photocurrent. Despite that minimal energy use, the nanosheets reached a sensitivity of 800 amperes per watt. Standard commercial sensors typically reach around 10 amperes per watt.
The team then used this property to build a stacked, color-selective sensor. The first gallium-doped zinc oxide layer detects the full visible spectrum using its photoactive trap states. After red light is filtered out, a second layer detects the remaining wavelengths. The design allows each layer to do its job without blocking what the next layer needs to see.
Beyond smartphones, the researchers noted several other possible applications. The nanosheets can withstand temperatures up to 400 degrees Celsius, or 752 degrees Fahrenheit, making them potentially useful in space hardware, automotive systems, and medical endoscopes, where both compact size and heat resistance matter.
The findings were published in ACS Nano. The Nagoya University team has not announced a timeline for commercial development.
