Direct probing of gate-bias stress effect in organic transistors by electron spin resonance spectroscopy

作者：Tanaka Hisaaki^*; Sawada Eishi; Azuma Kenjiro; Kuroda Shin ichi

来源：Applied Physics Express, 2015, 8(5): 051603.

DOI：10.7567/APEX.8.051603

The origin of gate-bias stress effect in organic field-effect transistors of poly(9,9-dioctylfluorene-co-bithiophene) has been studied by the direct observation of charge carriers using electron spin resonance. Stressed devices exhibited a remarkable decrease in polaron concentration, demonstrating the formation of nonmagnetic trap charges. The observed spin-charge relation excludes the formation of nonmagnetic bipolarons, which suggests that the trap charges are not in semiconducting layers but in the gate dielectrics. The results are consistent with the previously proposed migration of protons into dielectrics, produced by oxygen/water redox reactions. The suppression of the stress effect by adopting a topgate device geometry, sealing water vapor, further supports the mechanism.

• 出版日期2015-5