We studied the optical and electrical properties of the amorphous indium gallium zinc oxide thin‐film transistors (a‐IGZO TFTs). To develop a‐IGZO density‐of‐states model, intrinsic a‐IGZO optical properties such as optical band gap and Urbach energy, and TFT characteristics under illumination are investigated. During the a‐IGZO TFTs illumination with the wavelengths ranging from 460 to 660 nm, the off‐state drain current only slightly increases while a large increase was observed for the wavelength below 400 nm. Threshold voltage and subthreshold swing are also only slightly modified between 460 to 660 nm, while field‐effect mobility is almost unchanged in the investigated photon energy range. The observed results are consistent with the a‐IGZO optical energy band gap of about 3.05 eV. This study suggest that the a‐IGZO TFTs are light sensitive above 3.0 eV and photogenerated electrons are more mobile than holes within device channel region.

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Organic thin-film transistors (OTFTs) with high transmittance and low photosensitivity have been demonstrated. By using titanium dioxide nanoparticles as the additives in the polymer gate insulators, the level of device photoresponse has been reduced. The device shows simultaneously a high transparence and a minimal threshold voltage shift under white light illumination. It is inferred that the localized energy levels deep in the energy gap of pentacene behave as the recombination centers, enhancing substantially the recombination process in the conducting channel of the OTFTs. Therefore, the electron trapping is relieved and the shift of threshold voltage is reduced upon illumination.

We reported on organic thin-film transistors (OTFTs) with high dielectric constant polymer, poly(2,2,2-trifluoroethyl methacrylate) (PTFMA), as the gate dielectric. In top-contact OTFTs, the field-effect mobility was enhanced by applying a dielectric buffer layer poly(α-methylstyrene) to the bare PTFMA. After improving interfacial affinity within the active layer/dielectrics, deposited pentacene grain size and device performance were enhanced dramatically. The corresponding mobility, threshold voltage, and on/off current ratio were 0.70 cm2 V−1 s−1, −10.5 V, and 5.4×105, respectively. The moderately improved interface also suppressed the hole-trapping effect, which led to less hysteresis and minimized threshold voltage shift.