Organic-in organic hybrid solid solar cells were fabricated by using a conjugated polymer (MDMO-PPV) and SnO2 nanoparticles chemically modified with C60C(COOH)(2). The cell performance was improved by the chemical modification, suggesting that the modification with photoelectrochemically active organic materials is useful for establishing good electronic junction at the ofganic-inorganic interface. The short-circuit current density J(SC) increased with increasing thickness of MDMO-PPV up to 40nm, and then decreased gradually. This thickness dependence was explained by the fluorescence quenching of MDMO-PPV by Au electrode and the film resistance of MDMO-PPV. (C) 2007 Elsevier B.V. All rights reserved.