By strictly controling the cooling and heating rate for reactor and using generous hot deionized water to rinse the deposition

the high purity organic semiconductor material 3

4

9

10 perylenetetracarboxylic dianhydride (PTCDA) was preparde with raw material 1.8-naphthalic anhydride. Sublimated in vacuum

the purity of PTCDA was higher than 99% by analyzing purity with Varian high efficiency liquid phase colormetric spectrum. The measurement and analysis of HP5988A type mass spectrum of the sample is located at 392

which is consistent with the molecular weight of PTCDA. The measurement and analysis of the infrared absorption spectrum of the sample show it has anhydried and benzene base. The hydrogen atom's ascription was analyzed by nuclear magnetic resonance spectrum. X-ray diffraction spectrum shows PTCDA is monoclinic and its thin film deposition is preferred orientation. The analysis of the visible absorption spectrum shows that the absortion edge exists between 560~410nm which is located at the blue and green range. At the same time obvious exciton atsorption peak exists and the exciton band gap is 0.8eV

For 540nm wave

the relative absorption Intensity can be about 78%. For 500nm wave

the relative absorption intensity decreases to 50%. With the decrease of the incident wavelength

the relative intensity decreases linearly. For visible wave length larger than 570nm

it is transparent.