Organic Bidirectional Phototransistors Based on Diketopyrrolopyrrole and Fullerene

Abstract

It is shown that simple bilayer devices consisting of the diketopyrrolopyrrole (DPP) monomer Ph-TDPP-Ph as donor and C60 as acceptor feature J–V-characteristics of a bidirectional organic phototransistor where illumination intensity plays the role of the gate voltage as compared to a conventional field-effect transistor. The output current may therefore be controlled both electrically and optically. The underlying mechanism is based on the good charge transport in Ph-TDPP-Ph and C60, the intrinsic dissociation properties of C60, and the presence of an injection barrier for holes. In addition to this, it is demonstrated that the observed behavior of the DPP/C60 system allows the realization of basic logic elements like NOT-, AND-, and OR-Gates, which may provide the basis for advanced analog and digital applications.