The preparation method and test measurements of solar cells and photo-diodes having Metal-Organic thin film-Semiconductor structures have been described. Organic thin films with thicknesses in the range of 80-120 nm have been deposited on silicon substrates using a sublimation technique. The conversion efficiency of these solar cells shows an improvement by a factor of three over M-Si Schottky-type devices. The photo-diodes show stable and reproducible performances and the calculated quantum efficiency was found to be of the order of unity.