Optoelectronics
Imec and Holst Centre Unveil Fully-Organic Imager
At the International Image Sensor Workshop, imec and Holst Centre presented a large-area fully-organic photodetector array fabricated on a flexible substrate. The imager is sensitive in the wavelength range suitable for x-ray imaging applications.
BecaThe presented imager is sensitive in the wavelength range between 500 and 600 nm, making it compatible with typical scintillators and therefore suitable for x-ray imaging applications. It was fabricated by thermally evaporating an ultrathin (submicron) photosensitive layer of small organic molecules (SubPc/C60) on top of an organic readout circuit. A semi-transparent top contact enables front-side illumination. The readout backplane was manufactured on six inch foil-laminated wafers. It consists of pentacene-based thin-film transistors (TFTs) in arrays of 32x32 pixels with varying pitch (1 mm and 200 µm). To prevent degradation of the organic semiconductors in the air, the photodetector array is encapsulated. The imager was characterized under illumination with a calibrated green light-emitting diode (LED), yielding a linearly increasing photocurrent from the incident power of 3 µW/cm2. Dark current density is below 10-6 A/cm2 at a bias voltage of -2V.
This latest achievement is a significant step forward in not only finding the optimal materials, but pinpointing the best ways to process materials into reliable organic circuits and systems with state-of-the-art performance,” said Paul Heremans, technology director at the imec/Holst Centre. “Once again, we’re proud to demonstrate how imec’s top-notch research that leads to relevant industrial solutions, and subsequently brings added value to our partners’ businesses.”