Enhanced efficiency of organic photovoltaic cells with Sr2SiO4:Eu2+ and SrGa2S4:Eu2+ phosphors

We report the effect of yellow Sr2SiO4:Eu2+ and green SrGa2S4:Eu2+ phosphors on the efficiency of organic photovoltaic (OPV) cells. Each phosphor was coated on the back side of indium tin oxide (ITO)/glass substrates by spin coating with poly(methyl methacrylate) (PMMA). The maximum absorption wavelength of the active layer in the OPV cells was similar to 512 nm. The emission peaks of Sr2SiO4:Eu2+ and SrGa2S4:Eu2+ were maximized at 552 nm and 534 nm, respectively. The short circuit current density (J(SC)) and power conversion efficiency (PCE) of the OPV cells with Sr2SiO4:Eu2+ (8.55 mA/cm(2) and 3.25%) and with SrGa2S4:Eu2+ (9.29 mA/cm(2) and 3.3%) were higher than those of the control device without phosphor (7.605 mA/cm(2) and 3.04%). We concluded that phosphor tuned the wavelength of the incident light to the absorption wavelength of the active layer, thus increasing the J(SC) and PCE of the OPV cells. (c) 2013 Elsevier B.V. All rights reserved.