Researchers at Siemens may have come up with a new manufacturing method that will replace silicon x-ray detectors with cheaper polymer ones. Additionally, the technology allows for flexible detectors that can be developed for special applications.
From MIT Tech Review:
The Siemens researchers make their photodiodes by spraying water-based solutions containing two kinds of polymers through a metal mask onto a glass substrate. They put down, first, several layers of a polymer with low conductivity, then several layers of a polymer with high conductivity.
The use of two different polymers is crucial. When a photon hits the polymer photodiode, it excites an electron, leaving a positive “hole” behind; to read the resulting electrical signal, the diode has to carry the electron away from the hole. The interface between the two layers of polymers helps this separation to occur: the low-conductivity polymer carries the positive holes, while the other carries the electron to an electrical contact where it can be read.