Method of using offset gated gap-cell thin film device as a photosensor

Abstract

A method of utilizing a thin film device as a photosensor. The thin film device comprises a substrate upon which is deposited a charge transport layer, first and second injecting electrodes in low electrical resistance contact with the charge transport layer, the injecting electrodes being laterally spaced from one another, a gate electrode spaced normally from the first and second injecting electrodes and located opposite the first injecting electrode, for controlling injection therefrom, and laterally offset from the second injecting electrode, and a gate dielectric layer separating the gate electrode from the first and second injecting electrodes and the charge transport layer. The method of utilization comprises applying a first electrical bias of a first magnitude to the first injecting electrode, applying a second electrical bias of a second magnitude to the second injecting electrode, inhibiting charge injection from the first injecting electrode by applying a third electrode bias to the gate electrode of a third magnitude, and illuminating the charge transport layer. The photosensor may be selectively operated in a unity gain mode or in a variable gain mode, wherein said unity gain mode is achieved by causing the second magnitude to be greater than the first magnitude and the variable gain mode is achieved by causing the second magnitude to be less than the first magnitude.