Doping Indium Oxide Films with Amino‐Polymers of Varying Nitrogen Content Markedly Affects Charge Transport and Mechanical Flexibility

Here, correlations between polymer structure and charge transport in solution‐processed indium oxide, In 2 O 3 :polymer blend flexible thin film transistors (TFTs) are investigated using four polymers having electron‐donating amine functionalities (polyethyleneimine (PEI), poly(allylamine), polyethyleneimine ethoxylated (PEIE), and PVP‐NH 2 (PVP; poly(4‐vinylphenol)), and two PEI‐PEIE mixtures) with varied atomic amine nitrogen content (N%) of 12.6, 9.1, 6.9, 2.6, respectively. These amino‐polymers influence the semiconducting oxide film TFT electron mobilities via a delicate interplay of electron transfer/doping, charge generation/trap‐filling, film morphological/microstructural variations, which depend on the polymer structure, thermal stability, and N%, as well as the polymer content of the In 2 O 3 precursor and the carbon residue content in In 2 O 3 . Thus, increasing the N% from 0.0% in the control PVP to 12.6% in PEI increases the electron doping capacity, the polymer content of the blend formulation, and the blend TFT field‐effect mobility. Optimal polymer incorporation invariably enhances charge transport by as much as ≈2×, leading to a maximum carrier mobility of 8.47 ± 0.73 cm 2 V −1 s −1 on rigid Si/SiO x substrates and a remarkable 31.24 ± 0.41 cm 2 V −1 s −1 on mechanically flexible polyimide/Au/F:AlO x substrates with Al contacts. Furthermore, all of the polymers equally enhance the mechanical durability of the corresponding In 2 O 3 :polymer blend TFTs with respect to mechanical stress.