We report on the structural and optical properties of 6,13-pentacenequinone film deposited on n-Si by thermal evaporation at room temperature. According to X-ray diffraction, films were found to have good crystallinity and also to have two crystalline phases mixed. Photoluminescence (PL) spectra exhibited double peaks at 1.97 and 2.09 eV while the corresponding (double) peaks related to highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) transition were observed from direct absorption spectra at 2.94 and 3.11 eV The PL intensity was very strong under a UV illumination. It also seems that such a large Stokes shift as similar to 1 eV exist in this organic crystal system. Au/organic/n-Si structures using 6,13-pentacenequinone films on n-Si showed rectifying behavior but with a relatively high level of leakage current due to many traps in the organic film. (c) 2004 Elsevier B.V. All rights reserved.