Enhanced Open-Circuit Voltage in Subphthalocyanine/C₆₀ Organic Photovoltaic Cells

A double-heterostructure boron subphthalocyanine chloride (SubPc)/C₆₀ thin-film photovoltaic cell exhibits a more than doubled V_oc compared to a conventional copper phthalocyanine (CuPc)/C₆₀ cell under 1 sun AM1.5G simulated illumination. The lower oxidation potential of SubPc results in an increase in the energy difference between the lowest unoccupied molecular orbital of the acceptor-like material and the highest occupied molecular orbital of the donor-like material (referred to as the interface gap, I_g) by 400 meV. We attribute the significant increase in V_oc to this increase in I_g.