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Reduction of Fatigue in Squarylium Particulate Photoconductor by Electron Transport Doping

IP.com Disclosure Number: IPCOM000049431D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Balanson, RD: AUTHOR [+3]

Abstract

Squarylium-layered photoconductors, utilizing squarylium micro-crystals in an insulating binder as the charge generation layer (CGL), and diethylaminobenzaldyhydediphenylhydrazone DEH-doped polycarbonate as the charge transport layer (CTL), have been shown to be quite useful for electrophotographic applications. This is because they have very good peak sensitivity, and also broad spectral response, extending towards 1 Mum in the near infrared. However, the effect of "light fatigue" in the layered photoconductor poses a potential problem in actual applications. The light fatigue effect is the lowering of sensitivity of a dark adapted sample due to the exposure to light. Exposure to red light with an applied electric field is most effective in causing light fatigue.

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Reduction of Fatigue in Squarylium Particulate Photoconductor by Electron Transport Doping

Squarylium-layered photoconductors, utilizing squarylium micro-crystals in an insulating binder as the charge generation layer (CGL), and diethylaminobenzaldyhydediphenylhydrazone DEH-doped polycarbonate as the charge transport layer (CTL), have been shown to be quite useful for electrophotographic applications. This is because they have very good peak sensitivity, and also broad spectral response, extending towards 1 Mum in the near infrared. However, the effect of "light fatigue" in the layered photoconductor poses a potential problem in actual applications. The light fatigue effect is the lowering of sensitivity of a dark adapted sample due to the exposure to light. Exposure to red light with an applied electric field is most effective in causing light fatigue. We have found that light fatigue can be substantially reduced when the CGL is doped with an electron-transporting material. We also found that fatigue due to dark conductivity is also reduced by such doping.

The incident light produces photo-carriers (electrons and holes) in the methyl squarylium (MeSq) crystals in an applied electric field. Most of the carrier generation occurs close to the interface between the CGL and the CTL because of the high extinction coefficient of the MeSq. The hole travels towards the CTL, and is injected into the CTL at a sufficiently high electric field (>10(5) V/cm). The electron tra...