Next-generation wide-bandgap semiconductors such as SiC, GaN, and Ga₂O₃ are being considered as potential replacements for current silicon-based power devices due to their high mobility, larger size, and production of high-quality wafers at a moderate cost. In this study, we investigate the gradual modulation of chemical composition in multi-stacked metal oxide semiconductor thin films to enhance the performance and bias stability of thin-film transistors (TFTs). It demonstrates that adjusting the Ga ratio in the indium gallium oxide (IGO) semiconductor allows for precise control over the threshold voltage and enhances device stability. Moreover, employing multiple deposition techniques addresses the inherent limitations of solution-processed amorphous oxide semiconductor TFTs by mitigating porosity induced by solvent evaporation. It is anticipated that solution-processed indium gallium oxide (IGO) semiconductors, with a Ga ratio exceeding 50%, can be utilized in the production of oxide semiconductors with wide band gaps. These materials hold promise for power electronic applications necessitating high voltage and current capabilities.

Two-dimensional materials have shown a great promise for the next-generation electronic materials due to their unique optical, physical, and chemical properties that are distinct from their bulk counterparts. Their atomic-level thickness, the feature for flexible tenability, and exposed huge surface allow various approaches for high-performance nanoscale devices. Especially, this review highlights the recent progress on two-dimensional dielectric nanosheets, which are obtained by cheap and mass-producible solution-based exfoliation process, accompanied by the preparation methods, various deposition methods, and the characteristics of devices using a dielectric nanosheet thin films. We also present a perspective on the advantages offered by this two-dimensional dielectric nanosheets for the upcoming future nanoelectonics.

In this study, composite transparent electrodes were fabricated either from a conductive polymer poly(3,4- ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) or silver nanowire (AgNW). Three transparent electrodes such as PEDOT:PSS, PEDOT:PSS and AgNW mixture, and AgNW were fabricated. As for a transparent electrode, measured sheet resistance values were 89.6, 60.6 and 28.6 Ω/sq, and the transmittance values were 80.2, 82.0 and 83.8% while surface roughness (Rq) values were 4.1, 8.1, 20.4 nm for PEDOT:PSS, PEDOT:PSS and AgNW mixture, and AgNW, respectively. To verify the overall performance of these composite electrodes, we applied these electrodes to the top electrode of the solution-processed organic solar cells (OSCs). PEDOT:PSS provided the best performance with a fill factor (FF) of 51.2% and a photoconversion efficiency (PCE) of 2.2%, while traditional metal top electrode OSC provided FF of 60.5% and PCE of 3.1%.

Solution-processed organic light-emitting diodes (OLEDs) have the advantages of low cost, fast fabrication, and large-area devices. However, most studies on solution-processed OLEDs have mainly focused on solution-processable hole transporting materials or emissive materials. Here, we report fully solution-processed green OLEDs including hole/electron transport layers and emissive layers. The electrical and optical properties of OLEDs based on solution-processed TPBi (2,2′,2″-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)) as the electron transport layer were investigated with respect to the spin speed and the number of layers. The performance of OLEDs with solution-processed TPBi exhibits a power efficiency of 9.4 lm/W. We believe that the solution-processed electron transport layers can contribute to the development of efficient fully solution-processed multilayered OLEDs.

We investigated the effect of different thin-film thicknesses (25, 30, and 40 nm) on the electrical performance of solution-processed indium-zinc-oxide (IZO) thin-film transistors (TFTs). The structural properties of the IZO thin films were investigated by atomic force microscopy (AFM). AFM images revealed that the IZO thin films with thicknesses of 25 and 40 nm exhibit an uneven distribution of grains, which deforms the thin film and degrades the performance of the IZO TFT. Further, the IZO thin film with a thickness of 30 nm exhibits a homogeneous and smooth surface with a low RMS roughness of 1.88 nm. The IZO TFTs with the 30-nm-thick IZO film exhibit excellent results, with a field-effect mobility of 3.0(±0.2) cm²/Vs, high Ion/Ioff ratio of 1.1×10⁷, threshold voltage of 0.4(±0.1) V, and subthreshold swing of 0.7(±0.01) V/dec. The optimization of oxide semiconductor thickness through analysis of the surface morphologies can thus contribute to the development of oxide TFT manufacturing technology.

In this study, we developed the solution-processed PMMA-HfOx hybrid ReRAM devices to overcome the respective drawbacks of organic and inorganic materials. The performances of PMMA-HfOx hybrid ReRAM were compared to those of PMMA- and HfOx-based ReRAMs. Bipolar resistive switching behavior was observed from these ReRAMs. The PMMA-HfOx hybrid ReRAMs showed a larger operation voltage margin and memory window than PMMA-based and HfOx-based ReRAMs. The reliability and electrical instability of ReRAMs were remarkably improved by blending the HfOx into PMMA. An Ohmic conduction path was commonly generated in the LRS (low resistance state). In HRS (high resistance state), the PMMA-based ReRAM showed SCLC (space charge limited conduction). the PMMA-HfOx hybrid ReRAM and HfOx-based ReRAM revealed the Pool-Frenkel conduction. As aresult of flexibility test, serious defects were generated in HfOx film deposited on PI (polyimide) substrate. On the other hand, the PMMA and PMMA-HfOx films showed an excellent flexibility without defect generation.

Effect of multi-stacked layer (MSL), 0.1 mol (M) and 0.3 mol (M) hafnium oxide (HfO2)alignment layers were fabricated via a solution-process for LCs orientation. The solutions were spin-coated and annealed in a furnace. MSL consists of three sub-layers using 0.1 M solution,mono-layer (ML) is composed of 0.3 M HfO2 solution. Then ion-beam irradiation was treated with 1.8keV for 2 min. HfO2-based LC cells were investigated through photographs, pre-tilt angle using crystal rotation method, X-ray photoelectron spectroscopy (XPS) measurement, and surface roughness using atomic force microscopy(AFM) for their characteristic research. Good LC orientation characteristics were observed on MSL HfO2 surface. The LC alignment mechanism on MSL HfO2 and ML HfO2 surfaces was attributed to van der Waals (VDW) interaction between the LC molecular and substrate surface.

Thin-film transistors(TFTs) with silicon zinc tin oxide(SZTO) channel layer are fabricated by solution-process. The threshold voltage (Vth) shifted toward positive directly with increasing Si contents in SZTO system. Because the Si has a lower standard electrode potential (SEP) than Sn, Zn, thus degenerate the oxygen vacancy (VO). As a result, the Si act as carrier suppressor and oxygen binder in the SZTO as well as a Vth controller.

Thin-film transistors(TFTs) with magnesium zinc tin oxide(MZTO) channel layer are fabricated by solution-process. The threshold voltage (Vth) shifted toward positive directly with increasing Mg contents in MZTO system. Because the Mg has a lower standard electrode potential (SEP) than Sn, Zn, thus degenerate the oxygen vacancy (VO). As a result, the Mg act as carrier suppressor and oxygen binder in the MZTO as well as a Vth controller.