Bright-eyed polymer

Light sensors—photodetectors—have myriad uses in scientific, industrial, and consumer settings: Digital cameras, environmental monitors, remote controls, surveillance equipment, and biosensors are just a few applications. Most photodetectors are made from inorganic semiconductors and are sensitive in some limited waveband in the range between IR and UV. A new photodetector, however, that uses a semiconducting polymer shows good responsiveness from UV (300 nm) to near-IR (1450 nm), as shown in the figure. The polymer is a small-bandgap semiconductor that exhibits photo-induced, ultrafast electron transfer to fullerenes—blended with the polymer in the form of PC₆₀BM. Sandwiched between two electrodes, the two materials form a phase-separated blend with interpenetrating donor and acceptor networks. Because the new light sensor covers nearly the entire solar spectrum at Earth’s surface, the researchers—led by Alan Heeger of the University of California, Santa Barbara, and CBrite Inc—note that it holds promise for photovoltaic cells. The next step is to make addressable arrays of these broadband, high-detectivity photodetectors. (X. Gong et al. , Science , in press, http://dx.doi.org/10.1126/science.1176706 .)