Fast response organic photodetectors with a thick photoconversion region and fullerene transport layer

Abstract

Organic photodetectors were prepared based on polymer-fullerene blended heterojunctions using Poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and Phenyl-C61-Butyric-Acid-Methyl Ester (PCBM). In order to investigate and improve the sensitivity to short optical pulses, 5–10 micrometer thick layers were fabricated. A dual-solvent draw blade technique was developed to simplify the heterojunction production. The increased thickness resulted in a drastic reduction to the dark current. Both electrically inert nanoparticles and an evaporated fullerene interlayer were found to further improve the device performance. The external quantum efficiency was measured, as well as the fast pulse response in the limit of low photocarrier injection. Results showed a sensitivity to pulses of very small energy, 100 fJ, largely aided by a dark current that was below 10 nA/cm2.