Effect of UV and Water on Electrical Properties at Pre- and Post-Annealing Processes in Solution-Processed InGaZnO Transistors.

There are some reports related to applications of ultraviolet (UV) and water to enhance the electrical performance of metal oxide thin-film transistors (TFTs). We recently discovered that treatment timing and treatment method are also important for a good metal oxide thin-film formation. There are different influences on the metal oxide TFTs' electrical properties based on the UV irradiation and water treatment timing. The field-effect mobility of TFTs treated with UV-irradiation and water, which was spin-coated on the UV-irradiated film after pre-annealing, increased to 4.71 cm²V-1s-1 and 6.41 cm²V-1s-1. This was higher than the 3.39 cm²V-1s-1 field-effect mobility of non-treated TFTs. On the other hands, TFTs which were fabricated by the same method, with only varying the treatment time, after post-annealing, exhibited the tendency to show a decrease in field-effect mobility to 1.93 cm²V-1s-1 and 1.32 cm²V-1s-1, gradually, showing a contrasting tendency with the former conditions.

Numerical Design of Carrier Transporting Layer in Top-Gate InGaZnO Thin-Film Transistors for Controlling Potential Energy.

Top-gate amorphous indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) are designed with numerical analysis to control their electron potential energy. Design simulations show the effects of structural design on the electrical characteristics of these TFTs. In particular, the thicknesses of the channel (tch) and conducting (tc) layers, which play vital roles in TFT electrical performance, are varied from 1 to 50 nm to investigate the effect of thicknesses on the electron potential energies of the channel region and the electrode-semiconductor interfaces. The potential energies are precisely optimized for efficient charge transport, injection, and extraction, thus enhancing the electrical performance of these devices. It is also demonstrated that tch mainly affects mobility and threshold voltage, while tc mainly affects on-current. An acceptable threshold voltage of 0.55 V and high mobility of 14.7 cm²V-1s-1 are obtained with a tch of 30 nm and tc of 10 nm. Controllability of the electron potential energies and electrical performance of IGZO TFTs by means of structural design will contribute to realization of next-generation displays that have large areas and high resolutions.

Theoretical Analysis of Prospects of Organic Photovoltaics as a Multi-Functional Solar Cell and Laser Power Converter for Wireless Power Transfer.

Few reports have researched on utilization of laser power conversion systems for wireless power transfer in aeronautical applications. III-V compound semiconductors are commonly used as photovoltaic (PV) power converters in the previous studies. We propose the prospects of using organic absorbers as PV power converters. For laser power conversion to be applied for portable devices, the PV module should be easily processable, thin, low-weight, and printable on flexible substrates. Organic PVs provide all the above advantages, and thus, could serve as a potential candidate for laser power harvesting applications. Moreover, they can also be made transparent, which could be utilized in power harvesting lamination coatings and windows. We had simulated the possibility of using single-junction and tandem photovoltaic structures for 670 nm and 850 nm laser power harvesting. FDTD simulations were conducted to optimize the PV structure in order to maximize the absorption at the laser wavelengths. A maximum PCE of 16.17% for single-junction PV and 24.85% for tandem PV was theoretically obtained.

Effect of High-Speed Blade Coating on Electrical Characteristics in Polymer Based Transistors.

We explore the effect of high-speed blade coating on electrical characteristics of conjugated polymer-based thin-film transistors (TFTs). As the blade-coating speed increased, the thickness of the polymer thin-film was naturally increased while the surface roughness was found to be unchanged. Polymer TFTs show two remarkable tendencies on the magnitude of field-effect mobility with increasing blade-coating speed. As the blade-coating speed increased up to 2 mm/s, the fieldeffect mobility increased to 4.72 cm²V-1s-1. However, when the coating speed reached 6 mm/s beyond 2 mm/s, the field-effect mobility rather decreased to 3.18 cm²V-1s-1. The threshold voltage was positively shifted from 2.09 to 8.29 V with respect to increase in blade-coating speed.