Near-infrared imaging with quantum-dot-sensitized organic photodiodes

Solution-processed photodiodes with infrared sensitivities at wavelengths beyond the bandgap of silicon (corresponding to a wavelength of ∼1,100 nm) would be a significant advance towards cost-effective imaging. Colloidal quantum dots are highly suitable as infrared absorbers for photodetection, but high quantum yields have only been reported with photoconductors1,2,3. For imaging, photodiodes are required to ensure low-power operation and compatibility to active matrix backplanes4. Organic bulk heterojunctions5 are attractive as solution-processable diodes, but are limited to use in the visible spectrum. Here, we report the fabrication and application of hybrid bulk heterojunction photodiodes containing PbS nanocrystalline quantum dots as sensitizers for near-infrared detection up to 1.8 µm, with rectification ratios of ∼6,000, minimum lifetimes of one year and external quantum efficiencies of up to 51%. By integration of the solution-processed devices on amorphous silicon active matrix backplanes, we demonstrate for the first time near-infrared imaging with organic/inorganic hybrid photodiodes. Near-infrared imaging with solution-processed organic–inorganic hybrid photodiodes is demonstrated for the first time. The hybrid bulk-heterojunction photodiodes contain PbS nanocrystalline quantum dots as sensitizers for the detection of light of up to 1.8 µm in wavelength, have a minimum lifetime of one year, and external quantum efficiencies of up to 51%.