Flexible solar cells based on copper phthalocyanine and buckminsterfullerene

Flexible solar cells based on copper phthalocyanine (CuPc) and buckminsterfullerene (C60) were fabricated on flexible indium-tin-oxide (ITO) coated polyethylene terephthalate (PET) substrates. Substrate temperature was found obviously affecting the molecular orientation of CuPc films and low substrate temperature should be adopted in order to transport charges perpendicular to substrate surface. For planar heterojunction cell PET-ITO/CuPc/C60/CuPc (10 nm)/Al, the appropriate thickness of CuPc layer and C60 layer was 40 and 80 nm, respectively, in view of light absorption and power conversion efficiency. For hybrid planar-mixed molecular heterojunction cell PET-ITO/CuPc/CuPc:C60/C60/CuPc (10 nm)/Al, 33%(mole) of CuPc in CuPc:C60 blend layer resulted in well-distributed micro grains, which helped to improve photovoltaic performance. As the thickness of blend layer was increased to 90 nm, 0.85% of power conversion efficiency could be obtained. Bending test showed that no significant change happened in photovoltaic performance as tensile curvature up to 1.2 cm−1 and compressive curvature up to 1.35 cm−1, respectively.