Quasi-surface emission in vertical organic light-emitting transistors with network electrode.

We demonstrate a vertical-type organic light-emitting transistor (VOLET) with a network electrode of closed topology for quasi-surface emission. In our VOLET, the spatial distribution of the surface emission depends primarily on the relative scale of the aperture in the network electrode to the characteristic length for the charge carrier recombination. Due to the closed topology in the network of the source electrode, the charge transport and the resultant carrier recombination are substantially extended from individual network boundaries toward the corresponding aperture centers in the source electrode. The luminance was found to be well-controlled by the gate voltage through an organic semiconducting layer over the network source electrode.