Applications, photoconductors controls

Fig. 11 shows the photoswitching of the injection current. Upon UV irradiation, the hole injection current increased, while decreasing to zero on irradiation with visible light. Very thin amorphous diarylethene film as thin as 0.2 pm could also control the hole injection to the organic hole transport layer (Fig. 9b). These results are potentially applicable to optical memory-type organic photoconductors.

Photodetector — Device used to detect photons. After a long period having only thermal photodetectors, quantum photodetectors based on photocurrent were developed and are used quite widely in applications such as photographic meters, flame detectors and lighting control. In the late 1950s the p-i-n photodiode, simply referred to as photodiode, was developed and now is one of the most common photodiodes. There are several types of photodetectors, the most adequate depending on the specific application, like photoconductors, p-i-n photodiodes, Schottky-barrier photodiodes, charge-coupled... 

Semiconductor devices, the most common photodetectors, are of two main types. The photoconductor is effectively a radiation-controlled resistance, while the photodiode is similar to the vacuum version. The photoconductor is limited to specialized applications, while the photodiode and its internal multiplication form, the avalanche photodiode, have universal application. 

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