Organic photovoltaic cells with copper (Ⅱ) tetra-methyl substituted phthalocyanine

Efficient heterojunction organic photovoltaic (OPV) cells are fabricated based on copper tetra-methyl phthalocyanine (CuMePc) as donor and fullerene (C_(60)) as acceptor. The power conversion efficiency of CuMePc/C_(60) OPV cell (2.52%) is increased by 88% compared with that of the non-peripheral substituted copper phthalocyanine (CuPc)/C60 OPV cell (1.34%). The introduction of methyl substituent leads to stronger π–π interaction of CuMePc (~ 3.5 A) than that of CuPc (~ 3.8 A). The efficiency improvement is attributed to the enhanced carrier mobility of CuMePc thin film (1.1×10~(-3) cm~2/V·s) and better film morphology by introducing methyl groups into the periphery of CuPc molecule.