TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Composition: The solar cell back sheet further includes contact layer.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The content of long afterglow luminescent material is 0.05-50 wt.%. The insulating light-emitting material includes 70-85 wt.% insulating base material, 10-25 wt.% ultraviolet absorption material, and 5-12 wt.% long afterglow luminescent material. The long afterglow luminescent material is chosen from rare-earth activated-sulfur compound, rare-earth activated alkaline-earth salt, rare-earth activated-aluminum compound, and rare-earth activated-silicate compound. The ultraviolet absorbing material is chosen from silicate, aminosilane compound, silica, titania, and fluorinated organic polymer. The activated sulfur compound is of formula: ASx:Euy:Tz:OmX (I), or MSx:Euy:A'z:B'm (II). The rare-earth activated alkaline-earth salt is of formula: aMO.bAl2O3.cSiO2.dX' (III) or aMO.bAl2O3.Eux.A''yB''z (IV). The rare-earth activated silicate compound is of formula: aM.bLn.cSiO4.dX.eEu.fLn' (V).A,M=Ca, Sr, Mg, or Ba;T=Er, Dy, La, Tm, Y, or Mn;X=F, Cl, or Br;x,y,z,m,a,b,c,d,e=0-25;A'=Er, Dy, La, Tm, Y or Mn;B'=Na, K, or Ag;X'=Ce, Tb, or Dy;A''=Ce, Tb, Dy, Nd, or Pr;B''=Sb, or Sn;Ln=Y, La, or Gd;andLn'=Dy, Ho, Er, Yb, Bi or Mn.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The insulating base material is chosen from polyethylene terephthalate plastics, high-density polyethylene, paper fiber and mica. The weather-proof material is chosen from fluorine material, silicon polymer, polyether ketone and polysulfone. The fluorine material is chosen from polyvinyl fluoride, polytetrafluoroethylene, polyvinylidene fluoride, chlorotrifluoroethylene-ethylene copolymer, and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer. The insulating adhesive material is chosen from polyolefin, polyester and (meth) acrylic polymer. The contact layer includes contact material chosen from polyethylene-vinyl ethyl acetate, polyethylene-vinyl acetate-crosslinked formaldehyde, thermoplastic polyolefin, thermosetting polyolefin, polyvinyl fluoride, polytetrafluoroethylene, polyvinylidene fluoride, chlorotrifluoroethylene-ethylene copolymer, and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer.