Transparent organic photodiodes with high quantum efficiency in the near infrared

We demonstrate organic photodiodes with a transparency of ∼80% throughout the visible spectrum and with up to ∼80% external quantum efficiency (EQE) in the near infrared under reverse bias. The diodes use thin films of soluble naphthalocyanine (Nc) molecules prepared by spin casting, with or without thermal annealing. Annealing of the naphthalocyanine layer preferentially orients the planar Nc molecules parallel to the substrate surface. Annealed diodes have improved EQE at zero bias and photoconductive gain at small reverse bias.