NOVELTY - A rare-earth complex is a complex containing a rare-earth element chosen from praseodymium, europium, samarium, terbium, dysprosium, holmium and erbium. At least one type of 0.8-1.7 fluorine-containing ligand (a) (A1-A6), 0.8-1.2 nitrogen-containing ligand (b) (B1-B7), and 0-1.4 dioxo-containing ligand (c) (C1-C14) are coordinated to the rare-earth element, each with respect to one atom of rare-earth elements.    USE - Rare-earth complex is used for resin solution and resin composition for wavelength conversion sheet and sealing agent for solar cell module (all claimed) e.g. anti-reflective film.    ADVANTAGE - The rare-earth complex has excellent light resistance with respect to europium complex, and provides solar cell module having high efficiency, ultraviolet light and blue light absorbing and emitting property.    DETAILED DESCRIPTION - A rare-earth complex is a complex containing a rare-earth element chosen from praseodymium, europium, samarium, terbium, dysprosium, holmium and erbium. At least one type of 0.8-1.7 fluorine-containing ligand (a) of formulae (A1-A6), 0.8-1.2 nitrogen-containing ligand (b) of formulae (B1-B7), and 0-1.4 dioxo-containing ligand (c) of formulae (C1-C14) are coordinated to the rare-earth element, each with respect to one atom of rare-earth elements. The number ( alpha ) of components of ligand (a) per rare-earth element, and the number ( gamma ) of component of ligand (c) satisfies the relation: 2( alpha )+( gamma )=3-3.4.    X1,X2=aryl, heteroaryl, -C(CH3)3, -CH3, -CF3, -C2F5, -C3F7, or -C4F9.    INDEPENDENT CLAIMS are included for the following:    (1) resin composition, which comprises the rare-earth complex and resin;    (2) resin solution, which comprises the rare-earth complex, resin, and a solvent;    (3) wavelength conversion sheet, which consists of the resin composition;    (4) sealing agent, which consists of the resin composition; and    (5) solar cell module, which has photovoltaic cell and the wavelength conversion sheet arranged at the light-receiving surface side of the photovoltaic cell.