Low-voltage p-channel, n-channel and ambipolar organic thin-film transistors based on an ultrathin inorganic/polymer hybrid gate dielectric layer

A key issue in research into organic thin-film transistors (OTFTs) is low-voltage operation. In this study, we fabricated low-voltage operating (below 3V) p-channel, n-channel and ambipolar OTFTs based on pentacene or/and C₆₀ as the active layers, respectively, with an ultrathin AlO_X/poly(methyl methacrylate co glycidyl methacrylate) (P(MMA–GMA)) hybrid layer as the gate dielectric. Benefited from the enhanced crystallinity of C₆₀ layer and greatly reduced density of electron trapping states at the interface of channel/dielectric due to the insertion of ultrathin pentacene layer between C₆₀ and P(MMA–GMA), high electron mobility can be achieved in present pentacene/C₆₀ heterostructure based ambipolar OTFTs. The effect of the thickness of pentacene layer and the deposition sequence of pentacene and C₆₀ on the device performance of OTFTs was studied. The highest electron mobility of 3.50 cm²/V s and hole mobility of 0.25 cm²/V s were achieved in the ambipolar OTFT with a pentacene (3.0 nm)/C₆₀ (30 nm) heterostructure.