Direct mass spectrometry investigation on Pentacene thin film oxidation upon exposure to air

Although the degradation of Pentacene-based thin-film-transistors upon exposure to air has been widely observed, the degradation mechanism is not completely understood. We report a straightforward mass spectrometry investigation of Pentacene thin film oxidation upon exposure to air, mimicking the degradation of the transistor in its operational environment. We found that only a concomitant presence of humidity, oxygen, and light can produce a significant oxidation. Several oxidation products, including impurities of the starting material, are clearly identified and their percentage roughly estimated. The collected data cannot be fully explained with through conventional reaction mechanisms, suggesting that a more complicated scenario involving water, oxygen, and light should be studied.