A printing process for high-resolution transfer of all components for organic electronic devices on plastic substrates has been developed and demonstrated for pentacene (Pn), poly (3-hexylthiophene) and carbon nanotube (CNT) thin-film transistors (TFTs). The nanotransfer printing process allows fabrication of an entire device without exposing any component to incompatible processes and with reduced need for special chemical preparation of transfer or device substrates. Devices on plastic substrates include a Pn TFT with a saturation, field-effect mobility of 0.09 cm 2 (Vs) -1 and on/off ratio approximately 10 4 and a CNT TFT which exhibits ambipolar behavior and no hysteresis.

Articles you may be interested inFabrication and characterization of metal-molecule-silicon devices Appl. Phys. Lett. 91, 033508 (2007); Trapping and detrapping of electrons photoinjected from silicon to ultrathin SiO 2 overlayers. I. In vacuum and in the presence of ambient oxygen Photoelectron emission microscopy ͑PEEM͒ has been used to investigate simple device structures buried under ultrathin oxides. In particular, we have imaged Au-SiO 2 and p-type Si-SiO 2 structures and have demonstrated that PEEM is sensitive to these buried structures. Oxide overlayers ranging up to 15.3 nm were grown by systematically varying the exposure time of the structures to a plasma-enhanced chemical-vapor deposition process. The change in image contrast as the oxide thickness increases was used to quantify the inelastic mean-free path of low-energy photoelectrons ͑ϳ1 eV͒ in amorphous silicon dioxide. For Au structures we find that the dominant mean-free path for photoelectrons in the overlying oxide is about 1.18Ϯ0.2 nm. Yet, we find a residual observable signal from the buried Au structure through roughly 13 oxide attenuation lengths. The signal attenuation from the Au can be explained by the spread of the photoelectron energies and the energy dependence of the electron-phonon interaction. Similar intensity attenuation behavior is also seen from heavily p-doped silicon (10 20 cm Ϫ3 ) regions, but the signal is only observable through roughly 3.0 nm of oxide, and the signal from the 10 18 cm Ϫ3 regions is not detectable through the thinnest oxide layer of approximately 2.5 nm. Here, the energy spread ͑ϳ2.0 eV͒ is more narrowly distributed about the phonon loss energies, leading to the observed attenuation behavior from heavily p-doped silicon.

We demonstrate the application of photocurrent modulation spectroscopy in characterizing the performance of organic thin-film transistors. This technique provides a consistent framework to extract the mobility and density of free-carriers from experimental data without relying on assumed models of transport. Applying this technique to pentacene thin-film transistors shows that the mobility increases as ∼Vg1∕3, inconsistent with the prediction of hopping transport. The free-carrier density is approximately 1∕2 of the expected capacitive charge, and the mobility increases monotonically with the free carrier density, consistent with the trap and release model of transport.