Poly exciton ionization

The properties of ionized, or charged, oligofluorenes have been characterized and modeled [177-179]. One of these studies has found that charge carriers on oligo- or poly-fluorene backbones delocalize to a greater extent than a neutral exciton [177]. In addition, the fluorene backbone is more planar in the charged state than in the neutral state [178,179]. 

At first, diarsenic triselenide was used as the photoconducting material. Poly(A -vinyl carbazole) is now used. This polymer absorbs ultraviolet light, producing an exciton, which ionizes in an electric field. Poly(vinyl carbazole) behaves as an insulator in visible light, but can, however, be sensitized with certain electron donors to form a charge transfer complex. 

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