Flexible organic field-effect transistors with TIPS-Pentacene crystals exhibiting high electrical stability upon bending

•Flexible OFETs fabricated using HfO2/PVP gate dielectric and TIPS-Pentacene crystals.•OFETs were studied for stability of electrical characteristics upon bending up to 48 h.•Electrical characteristics degraded primarily due to increase in strain.•Strain induces increase in dielectric surface roughness leading to performance degradation.•Device performance is influenced more with magnitude of strain than its duration.

Flexible organic field-effect transistors with high electrical stability upon bending are demonstrated on indium tin oxide coated polyethylene terephthalate substrates with TIPS-Pentacene semiconductor crystals formed by drop casting on a hybrid gate dielectric consisting hafnium dioxide grown by atomic layer deposition and spin coated poly(4-vinylphenol). Fabricated devices exhibited excellent p-channel characteristics with field-effect mobility up to 0.12 cm2/Vs with high current on/off ratio >104 and low threshold voltage of −0.2 V. Device performance was slightly affected by mechanical strain applied by bending for 5 min with radius varying from 12.5 mm to as low as 5.0 mm; and a high stability in performance was demonstrated upon applying constant tensile strain for more than 48 h at bending radius of 5.0 mm. It was found that strain induced changes in the device performance primarily occur due to increase in dielectric surface roughness; and the semiconductor-dielectric interface uniformity is influenced more with magnitude of strain rather than its duration.

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