This thesis describes the development of electrical OFET characteristics under different environmental stresses. The OFETs described here are based on Polytriarylamine (PTAA) as the organic semiconductor and are processed by spincoating on flexible substrates. Over 1700 OFETs are processed in total and measured multiple times during the aging process to collect statistically significant data.
The first part describes the development of an automated measurement setup and a concept to extract circuit-relevant OFET parameters such as on- and off-current, mobility, threshold voltage and gate leakage current from the measured transfer and output curves. The measured OFET parameters are then analyzed in the unaged condition for different OFET geometries. An in depth analysis of geometry dependence and sample to sample variation for these parameters is given.
The samples are then aged under different environmental stresses, which mainly consist of atmospheric oxygen at room temperature and at 85°C in dry atmosphere and storage at 85°C and 85% relative humidity. The OFETs are measured regularly during storage under the different conditions for over 2000 h. Additional FT-IR measurements of the aged OFET materials complement the electrical tests. A theory for the aging behavior is developed according to the measured results and presented.