A near infrared organic photodiode with gain at low bias voltage

We demonstrate an organic photodiode with near infrared optical response out to about 1100 nm with a gain of ∼10 at 1000 nm under 5 V reverse bias. The diodes employ a soluble naphthalocyanine with a peak absorption coefficient of ∼105 cm−1 at 1000 nm. In contrast to most organic photodiodes, no exciton dissociating material is used. At zero bias, the diodes are inefficient with an external quantum efficiency of ∼10−2. In reverse bias, large gain occurs and is linear with bias voltage above 4 V. The observed gain is consistent with a photoconductive gain mechanism.