Researchers fabricated green absorbing transparent organic photodetectors that are highly sensitive and compatible with CMOS fabrication methods. They combined one of these green organic photodetectors with a silicon photodiode with red and blue filters to create an organic-silicon hybrid RGB imaging sensor. Credit: Sungjun Park, Ajou University
New green-light absorbing transparent organic photodetectors that are highly sensitive and compatible with CMOS fabrication methods have been developed and demonstrated by researchers. Incorporating these new photodetectors into organic-silicon hybrid image sensors could be useful for many applications. These include light-based heart-rate monitoring, fingerprint recognition, and devices that detect the presence of nearby objects.
“For organic photodetectors to be incorporated into mass-produced CMOS image sensors requires organic light absorbers that are easy to fabricate on large scales and can accomplish vivid image recognition and produce distinct images in the dark with a high frame rate,” said Sungjun Park from Ajou University in the Republic of Korea, who co-led the research team. “We developed transparent green-sensitive organic photodiodes that can meet these requirements.
“We introduced a bathocuproine :C60 mixed buffer layer as an electron transporting layer,” said Sungjun Park. “This gave the organic photodetectors exceptional characteristics, including higher efficiency and an extremely low dark current, which reduces noise.” This photodetector can be placed on a silicon photodiode with red and blue filters to create a hybrid image sensor.