Organic photoconductors photocurrent

Photocurrent — Contribution to the current in a -+ semiconductor due to photon incidence. For both inorganic and organic photoconductors the light intensity II and the photocurrent Jph are related by Iph = l[y where y is characteristic of the photoconducting system. In photovoltaic devices photocurrent denotes the difference between the -> current generated by the device under illumination and the current with the device in the dark, the dark current. See also photoconductivity. 

As in inorganic photoconductors, with organic dyes and other organic compounds, too, photocurrents and photovoltages may be observed without the application of auxiliary voltages. The following effects may be mentioned. 

Photoelectrochemical behavior of metal phthalocyanine solid films (p-type photoconductors) have been studied at both metal (93,94,95,96) and semiconductor (97,98) electrodes. Copper phthalocyanine vacuum-deposited on a Sn02 OTE (97) displayed photocurrents with signs depending on the thickness of film as well as the electrode potential. Besides anodic photocurrents due to normal dye sensitization phenomenon on an n-type semiconductor, enhanced cathodic photocurrents were observed with thicker films due to a bulk effect (p-type photoconductivity) of the dye layer. Meier et al. (9j>) studied the cathodic photocurrent behavior of various metal phthalocyanines on platinum electrodes where the dye layer acted as a typical p-type organic semiconductor. 

Photoconductivity is a typical phenomenon for many organic semiconductors. When a photoconductor is illuminated by light, which it is able to absorb, charge carriers are produced and consequently the conductivity of the material increases [198]. Several processes are responsible for the magnitude of a photocurrent within an organic solid [199, 200] ... 

---