Organic photodiodes to improve camera sensitivity
Scientists at the Fraunhofer Research Institution for Organics, Materials and Electronic Devices COMEDD in Dresden are now developing organic photodiodes (OPDs) that could increase the sensitivity of cameras.
The OPDs rely on organic materials such as dyes or pigments. ‘These kinds of OPD offer a range of advantages compared with inorganic components – they’re extremely lightweight, cheap to produce and can be used for flexible applications,’ explained COMEDD head of department Dr Olaf Hild.
Uses vary from tiny sensor elements for cameras or for bioanalytics, to large-scale, quality control applications. In lab-on-chip applications, for instance, OPDs can detect certain DNA sequences that have been tagged with fluorescent markers.
Hild explained how photodiodes help to increase a high-end camera’s light sensitivity: 'Integrating our organic photodiodes increases the light sensitivity of today’s CCD chips by providing a larger usable surface.'
OPDs can also be used to check the homogeneity of the colour composition or the brightness distribution of luminescent surfaces such as displays.
Unlike their silicon-based counterparts, OPDs can also be integrated into polymer films that can be applied to concave or curved surfaces. This could be used to develop quality control systems specially shaped to the product - for instance, entire car doors could be examined for scratches or any quality inconsistencies in the paintwork with an OPD.
It is particularly in such large-scale applications that OPDs offer a cheaper alternative to traditional technologies. While it is very difficult and expensive to cover large surfaces with silicon, OPDs can be applied to comparatively inexpensive materials using simple coating techniques. This means that the scientists can use established manufacturing techniques such as those used to manufacture organic photovoltaics, for example.