1. Field of the Invention
The present invention relates to optoelectronic devices, and more particularly, relates to organic photocurrent multiplication devices using organic semiconductors.
2. Background Art
Conventional photocurrent multiplication devices normally have a structure of a single-layer organic thin film sandwiched by two metal electrodes, in which the device is irradiated with a single light on one side to cause photocurrent multiplication (see M. Hiramoto, T. Imahigashi, M. Yokoyama, Applied Physics Letters, 64, 187 (1994), for example).
There is also known a “light to light” conversion device in which the photocurrent multiplication device described above and an organic electroluminescent device are layered on each other integrally (see M. Hiramoto, T. Katsume, M. Yokoyama, Oyo Buturi, 64, 1036 (1995), for example).
The conventional photocurrent multiplication device including a single-layer organic thin film described above only has a simple function of permitting photocurrent multiplication to occur when the device is irradiated with one light. Therefore, to apply the photocurrent multiplication device to an advanced optical device that controls light by use of two lights, such as an optical operator, a new function must be added. For example, to be provided with an AND function, the photocurrent multiplication device must be configured so that multiplication occurs only by irradiating the device with two lights simultaneously. It is, however, impossible for the conventional photocurrent multiplication device to be provided with such a function.
In view of the above, an object of the present invention is to provide an organic photocurrent multiplication device having an AND function of permitting photocurrent multiplication to occur only when the device is irradiated with two lights.