Compactly fused electron donor-acceptor (D-A) compounds, as exemplified with the tetrathiafulvalene (TTF) – benzothiadiazole (BTD) compound (1) and shown in Figure 1, constitute a class of redox-active materials with intriguing solid-state properties.[1] Combining D and A units in a planar π-conjugated molecular backbone is a promising strategy for obtaining a pronounced electrochemical amphotericity and strong photoinduced intramolecular charge-transfer (CT) transitions. Controlled chemical oxidation can induce the crystallization of fully or partially oxidized CT salts which may exhibit π-stacks, hence one-dimensional spin systems, with closely bound acceptor units along each of these strands (Figure 2). In case of compound 1, it results in a crystalline organic semiconductor exhibiting a room temperature conductivity of around 2 S cm-1. On the scale of a single D-A molecule, the detailed charge distribution can be investigated by different scanning probe methods.[2]