Browse Prior Art Database

TTF Vinyl Polymers as Photoconductive Matrices

IP.com Disclosure Number: IPCOM000089820D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 25K

Publishing Venue

IBM

Related People

Green, DC: AUTHOR [+2]

Abstract

In the last 10 years, speciality organic polymers of relatively high cost and low overall volume have become important to the electronics, photographic and electrophotographic industries. By virtue of their unique combination of properties, such as ease of large scale fabrication, mechanical flexibility and low replacement costs, these novel materials have gradually replaced some of the inorganic solids traditionally used in these applications. For vinyl main chain polymers which have been among the most important of these speciality organic polymers, improvements in physical properties and/or the discovery of new phenomena depend on the incorporation of new and different molecules on the polymer sites pendant to the main chain.

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TTF Vinyl Polymers as Photoconductive Matrices

In the last 10 years, speciality organic polymers of relatively high cost and low overall volume have become important to the electronics, photographic and electrophotographic industries. By virtue of their unique combination of properties, such as ease of large scale fabrication, mechanical flexibility and low replacement costs, these novel materials have gradually replaced some of the inorganic solids traditionally used in these applications. For vinyl main chain polymers which have been among the most important of these speciality organic polymers, improvements in physical properties and/or the discovery of new phenomena depend on the incorporation of new and different molecules on the polymer sites pendant to the main chain. This disclosure describes a new class of vinyl polymers and suggests their utility as "active polymer matrices" in photoconductive and photovoltaic applications.

It has been well established in the patent literature that microcrystalline dye aggregates dispersed in polymer matrices lead to photoconducting materials [1]. With electron donor groups on the polymer, such as in poly (vinyl carbazole), and n-type dye aggregates dispersed in the polymer film, the active matrix is p-type according to the following mechanism:

(Image Omitted)

Reactions (1), (2) and (3) indicate dye sensitization of the polymer matrix via electron transfer from the polymer to the dye aggregate, followed by field-induced hole hopping through the polymer matrix.

Although there has been almost no literature published which systematically relates efficiency of transport to the electronic nature of the molecules pendant to the vinyl polymer chain, it is reasonable to suggest that the following are desirable molecular criteria for improved electronic properties of the polymer matrix: (1) Low ionization potential. (2) Forms cation-radical reversibly. (3) Cation-radical (the hole state) is chemically stable. (4) Molecule or its ion known to interact in the solid state. (5) Wide range of chemistry available for molecular modifications.

However, virtually all of the active polymer matrices that have been discussed to date are composed of molecules that meet few, if any, of these desirable criteria. On the other hand, the heterofulvalene class of organic donors (see figure below), with X(i)=S, Se, etc.,

(Image Omitted)

are known to satisfy all these molecular criteria. Unfortunately, the few polymers [2,3,4] containing this donor that were previously synthesized buffer from a variety of defects including poor solubility, insulating bonding between donors, and low mole...