Laser-Induced Intrinsic and Dye-Sensitized Photoconductivity in β-Carotene Glass

Abstract

Photoconductivity is studied in thin films of β-carotenc glass, an amorphous mixture of β-carotene isomers. Photocurrents are produced by a pulsed dye laser and are on the order of microamperes. The mechanism for production of photocurrent is believed to be two-photon internal photoemission. Photoconduction is also investigated in a variety of organic dyes. These dyes and chlorophyll a are then used to sensitize the photoconduction of β-carotene glass to longer wavelengths than it would normally photoconduct. It is believed that chlorophyll and phthalocyanine donate holes to the carotene after photoexcitation, while the other dyes undergo an energy transfer process. The voltage, laser intensity, and wavelength dependences of the photocurrents are examined and compared with results from earlier studies.