Infrared Photodetectors and Image Arrays Made with Organic Semiconductors

Combining the strategies of introducing larger heteroatom, regio-regular backbone and extended branching position of side-chain, we developed polymer semiconductors (PPCPD) with narrow band-gap to construct the photosensing layer of thin-film photodiodes and image arrays. The spectral response of the resulting organic photodiodes spans from the near ultra-violet to short-wavelength infrared region. The performance of these short-wavelength infrared photodiodes in 900-1200 nm range achieved a level competitive with that of indium gallium arsenide-based inorganic crystalline detectors, exhibiting a specific detectivity of 5.55x10(12) Jones at 1.15 mu m. High photodetectivity and quantum efficiency in photodiode with amorphous/nanocrystalline thin-films of 100-200 nm thickness enabled high pixel-density image arrays without pixel-level-patterning in the sensing layer. 1 x 256 linear diode arrays with 25 mu m x 25 mu m pixel pitch were achieved, enabling high pixel-density short-wavelength infrared imaging at room temperature.