Factors influencing local potential drop in bottom-contact organic thin-film transistor using solution-processible tetrabenzoporphyrin

By exploiting atomic-force-microscope potentiometry, we have studied the local potential distribution in the solution-processible tetrabenzoporphyrin (BP) bottom-contact thin-film transistor under controlled atmospheres. It is found that abrupt and big potential drops mainly appeared at the domain boundaries and cracks in the BP film when the transistor was under operation, indicating a dominant influence of domain boundary and crack on the device performance. Exposure of the device to O2 drastically reduced the potential drops at some boundaries, which is the main reason for the improved device performance by O2 exposure.