Ultraviolet Photodetectors based on Semiconducting Polymers

There is a strategic need for detectors of ultraviolet (UV) radiation which are "solar blind". Such devices based on inorganic semiconductors with bandgaps larger than 3.25 eV are at an early stage of development. Organic semiconductors, by contrast,, offer advantages for use as emitters and detectors in the green, blue, and UV. Organic semiconducting polymers are intrinsically large bandgap materials. They are readily and inexpensively processed, either from solution in an appropriate solvent or from a melt. Preliminary results for photodiodes based on such polymers show a number of intriguing features: a sharp cutoff in responsibility at the semiconductor band edge, the possibility of tailoring this spectral cutoff by altering chemical structure, good UV sensitivity, and a relatively flat spectral response. Little is known about the noise characteristics or other potential limitations of these devices. UNIAX proposes a Phase I research program with the goal of establishing the viability of polymer photodiodes for solar blind UV detector applications. The proposed research will focus both on identifying appropriate materials, and on an investigation of the detector characteristics of devices based on them. Appropriate candidate materials have already been developed for the company's blue light emitting device program.