Short circuit current improvement in planar heterojunction organic solar cells by multijunction charge transfer

A multijunction structure was applied on an organic photovoltaic (OPV) device for broadening the absorption spectrum and enhancing the power conversion efficiency through charge transfer process. By inserting the tris[4-(2-thienyl)]amine (TTPA) into a boron subphthalocyanine chloride (SubPc)/C60OPV device, the short circuit current density (Jsc) showed a 47.5% increases from 3.05 to 4.50 mA/cm2in the bilayer planar heterojunction device, while the open circuit voltage (Voc) remained constant. Based on the single junction (TTPA/SubPc) device and photoluminescence absorption results, we confirmed both TTPA/SubPc and SubPc/C60junctions are contributing to the exciton dissociation process hence the efficiency enhancement.