n-Channel Polymer Field-Effect Transistors without Encapsulation Have over 21-Year Stability in Ambient Air

We report herein the ultrahigh stability of n-channel organic field-effect transistors (OFETs) based on ladder poly(benzimidazobenzophenanthroline) (BBL), without any encapsulation, which have remained fully functional after over 21 years of storage in ambient air, marking an unprecedented milestone for organic electronic devices. Although the BBL OFETs, fabricated in 2003 and 2011, had excellent functionality, the figures of merit slightly degraded from their original values. Thermal annealing of the aged OFETs enabled a complete reversal of the degradation process and full recovery of the electron transport properties. Trap density of states spectral analysis and characterization of OFET performance as a function of thermal annealing show that the ambient air-induced trapping sites accumulated at the semiconductor/dielectric interface over the long term are fully passivated. Our results provide evidence of over 21-year ambient air stability of BBL OFETs and offer insights into the potential design of next-generation semiconducting polymers and organic electronic devices with excellent stability.