The stability of organic thin film transistors (OTFTs) has become one of the most vital issues in this area of research. In this report, we investigated the stability of rubber stamp printed OTFTs. The electrical properties such as saturation field effect mobility, threshold voltage and on/off current ratio change significantly in ambient air condition. In order to analyze the degradation of the device, transistors were measured in vacuum, dry N2 and air environment as a function of time. In vacuum and dry N2 atmosphere, saturation field effect mobility and threshold voltage variations are relatively small compared to those measured in ambient condition.
To realize an air stable device, we applied a passivation layer which protects the device from oxygen or water molecules which is believed to be the source of the degradation. With the passivation layer, the threshold voltage shift was reduced suggesting that a proper passivation layer is a prerequisite in organic-based electronics.