Bis(5,7-dimethyl-8-hydroxyquinolinato)platinum(II) complex for efficient organic heterojunction solar cells

Organic photovoltaic (OPV) cells using metal(II) (Pt, Pd, Cu, and Ni) chelates of 8-hydroxyquinoline (Hq) or 5,7-dimethyl-8-hydroxy-quinoline (HMe(2)q) as an electron donor were fabricated by vacuum deposition. The bis(5,7-dimethyl-8-hydroxyquinolinato)platinum(II) [Pt(Me(2) q)(2)]-based OPVs showed the best performance with an open voltage (V(OC)) of 0.42 V, a short circuit current density (J(SC) ) of 14.8 mA cm(-2) , and a maximum power conversion efficiency (η(P) ) of 2.4%. The X-ray single-crystal structures together with the grazing incidence X-ray diffraction (GIXRD) data of thin film samples reveal that the peripheral methyl substituent(s) and platinum(II) ion are essential for the high degree of film crystallinity resulting in improved performance of the as-fabricated field-effect transistors (FETs) and OPV cells.