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Jianping. Gong, Satomi. Ohnishi, and Yoshihito. Osada
[Polymer Journal, Vol. 26, No. 6, pp 754-757, 1994]
Organic thin film devices attract special attention for potential to replace inorganic semiconductors in the development of large-area, lightweight, and inexpensive light-electricity conversion devices. Plasma polymerization is a unique technique for forming polymer thin films from almost all organic gas vapors. Extensive investigation of the electrical properties of plasma polymerized films using a wide variety of organic and metal containing monomer has been carried out and interesting results has been achieved. Studies on the photo conduction of plasma polymeric films have also extensively been carried out.
Tetracyanoquinodimethane (TCNQ) and its derivatives are strong electron acceptors, and investigation of their properties is of interest since a number of stable charge transfer complex crystals with high electrical conductivity can be formed from them by combining with a variety of electron donors.
We previously reported that TCNQ can be polymerized by plasma polymerization at 13.56 Hz to give polymeric films with conductivity from 10-10 to 10-6 Scm-1. Infrared, ultraviolet, and X-ray photoelectron spectroscopy were used to characterize structure, and the results as well as those from electrical measurements confirmed that a conjugated structure with delocalized p-electrons is formed in the films.
This paper reports the photo-current characteristics of two-layered organic thin films composed of plasma-polymerized TCNQ (p.p.TCNQ), copper phthalocyanine (CuPc)(p.p.CuPc), N-[3-(dimethylamino)propyl] acrylamid (DMAPAA) (p.p.DMAPAA), and 2-vinylpyridine (VP) (p.p.VP) or solution-casted polyethyleneimine (PEI) film (c.PEI). A two-layered polymeric cell shows rectification phenomena and sensitive photo responses presumably due to the formation of depletion layer at the interface of the two layers.
