pn-control and pn-homojunction formation of metal-free phthalocyanine by doping

The Fermi level (EF) of metal-free phthalocyanine (H2Pc), located at the center of the bandgap (4.4 eV), is shifted to 3.8 eV, close to the conduction band (3.5 eV), by cesium carbonate doping and shifted to 4.9 eV, close to the valence band (5.1 eV), by molybdenum oxide doping under oxygen free conditions. Formation of n- and p-type Schottky junctions and pn-homojunctions in single H2Pc films, confirmed by their photovoltaic properties, clearly demonstrates the formation of n- and p-type H2Pc.