NOVELTY - Composite particles (4) contain semiconductor particles (6) and inorganic compound-containing particles (8). The composition of inorganic compound-containing particles is different from the composition of semiconductor particles. The average particle diameter of primary particles of semiconductor particles is 1-10 nm. The average particle diameter of primary particles of inorganic compound-containing particles is 1-30 nm. The content of semiconductor particles is 30-90 volume% with respect to total content of composite particles.    USE - Composite particles are used for resin composition for forming wavelength conversion layer for photovoltaic device (all claimed). Uses include but are not limited to electroluminescent illumination, optical communication, electroluminescent display component, light emitting diode illumination, solar cell and bio-imaging.    ADVANTAGE - The resin composition containing the composite particles has excellent dispersibility. The wavelength conversion layer formed using the resin composition has excellent durability and luminescent property. The photovoltaic device has high efficiency and reliability.    DETAILED DESCRIPTION - Composite particles contain semiconductor particles and inorganic compound-containing particles. The composition of inorganic compound-containing particles is different from the composition of semiconductor particles. The average particle diameter of primary particles of semiconductor particles is 1-10 nm. The average particle diameter of primary particles of inorganic compound-containing particles is 1-30 nm. The average particle diameter of primary particles of composite particles is 20-100 nm. The content of semiconductor particles is 30-90 volume% with respect to total content of composite particles. INDEPENDENT CLAIMS are included for the following:    (1) resin composition, which contains the composite particles and curable resin;    (2) wavelength conversion layer (3), which is obtained by hardening layer containing resin composition; and    (3) photovoltaic device.    DESCRIPTION OF DRAWING(S) - The drawing shows sectional view of wavelength conversion layer and composite particles.    Wavelength conversion layer (3)    Composite particles (4)    Photoresist (5)    Semiconductor particles (6)    Inorganic compound-containing particles (8)