We have fabricated flexible organic field effect transistors (OFETs) on polyimide substrate with low hysteresis and low leakage current under repetitive bending. The insertion of an ultrathin atomic-layer-deposited Al2O3 layer in between spin-coated poly-4-vinyl phenol organic layers in a multistack hybrid gate dielectric for OFETs significantly improved stability in the electrical hysteresis during cyclic bending. The observed hysteresis stability for cyclically bent multistack hybrid OFET devices was attributed to efficient blocking of charges injected from the gate electrode due to improved mechanical stability. Cyclically bent samples showed no cracking for thinner Al2O3 layers in the multistack hybrid gate dielectrics. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3489944] All rights reserved.