Photoconductive element exhibiting persistent conductivity

Claim 1

A photoconductive insulating element having at least two layers comprising a charge-generation layer in electrical contact with a charge-transport layer, a. said charge-generation layer comprising a continuous, electrically insulating polymer phase and dispersed in said continuous phase a discontinuous phase comprising a finely-divided, particulate co-crystalline complex of (i) at least one polymer having an alkylidene diarylene group in a recurring unit and (ii) at least one pyrylium-type dye salt, said co-crystalline complex, upon exposure to activating radiation for said complex, capable of generating and injecting charge carriers into said charge-transport layer, b. said charge-transport layer being an organic composition comprising a p-type organic photoconductive charge-transport material capable of accepting and transporting injected charge carriers from said charge-generation layer, said charge-transport material having a polarographic oxidation potential between about +0.90 and +0.50 volts and the capability of forming chemically stable radical cations, and c. at least one of said charge-transport or said charge-generation layers comprising a protonic acid selected from the group consisting of substituted carbocyclic aromatic carboxylic acids, substituted phenols, substituted naphthols, substituted aliphatic and substituted alicyclic carboxylic acids, and substituted aromatic heterocyclic carboxylic acids, each of the aforementioned protonic acids characterized by the presence of one or more electron-withdrawing substituents such that the sum of the sigma values for the substituents of said protonic acids is equal to or greater than 1.0.