Amorphous InGaZnO x (a-IGZO) thin-film transistors (TFTs) are currently used in flat-panel displays due to their beneficial properties. However, the mobility of ∼10 cm2/(V s) for the a-IGZO TFTs used in commercial organic light-emitting diode TVs is not satisfactory for high-resolution display applications such as virtual and augmented reality applications. In general, the electrical properties of amorphous oxide semiconductors are strongly dependent on their chemical composition; the indium (In)-rich IGZO achieves a high mobility of 50 cm2/(V s). However, the In-rich IGZO TFTs possess another issue of negative threshold voltage owing to intrinsically high carrier density. Therefore, the development of an effective way of carrier density suppression in In-rich IGZO will be a key strategy to the realization of practical high-mobility a-IGZO TFTs. In this study, we report that In-rich IGZO TFTs with vertically stacked InO x , ZnO x , and GaO x atomic layers exhibit excellent performances such as saturation mobilities of ∼74 cm2/(V s), threshold voltage of −1.3 V, on/off ratio of 8.9 × 108, subthreshold swing of 0.26 V/decade, and hysteresis of 0.2 V, while keeping a reasonable carrier density of ∼1017 cm–3. We found that the vertical dimension control of IGZO active layers is critical to TFT performance parameters such as mobility and threshold voltage. This study illustrates the potential advantages of atomic layer deposition processes for fabricating ultrahigh-mobility oxide TFTs.

Synthesis of polyolefin (PO)-based block copolymers is of immense research interest. In this work, we report a strategy for the construction of polystyrene (PS)-block-PO-block-PS, a useful thermoplastic elastomer, directly from olefin and styrene monomers. Multinuclear zinc species Et­[Zn­(CH2)6] a ZnEt were prepared through successive additions of BH3 and Et2Zn to 1,5-hexadiene. Poly­(ethylene-co-propylene) chains were biaxially grown from the −(CH2)6– units in Et­[Zn­(CH2)6] a ZnEt via “coordinative chain transfer polymerization (CCTP)” using the pyridylaminohafnium catalyst. PS chains were subsequently grown in one pot from the generated polymeryl–Zn sites by subsequent introduction of the anionic initiator Me3SiCH2Li·(pmdeta) (pmdeta, pentamethyl­diethylenetriamine) and styrene monomers. The fraction of the extracted PS homopolymer grown from the Me3SiCH2 sites was low (homo-PS (g)/total PS (g), 15–22%). The gel permeation chromatography (GPC) curves shifted evidently after styrene polymerization, and change in the molecular weight (ΔM n, 39–56 kDa) was approximately twice the homo-PS M n (20–23 kDa), in accordance with attachment of the PS chains at both ends of the PO chains. Transmission electron microscopy analysis of the thin films showed segregation of the PS domains in the PO matrix to form spherical or wormlike rippled structures depending on the PS content. The prepared triblock copolymers exhibited elastomeric properties in the cyclic tensile test, similar to the commercial PS-block-poly­(ethylene-co-1-butene)-block-PS.

Ethylene tetramerization catalyst systems comprising a Cr(III) complex containing PNP ligands and methylaluminoxane (MAO) are useful for the production of 1-octene. However, a concern with these systems is the use of expensive MAO in excess. Herein, we report a catalytic system that avoids the use of MAO. Metathesis of CrCl 3 (THF) 3 and [(CH 3 CN) 4 Ag] + [B(C 6 F 5 ) 4 ] − afforded [L 4 Cr III Cl 2 ] + [B(C 6 F 5 ) 4 ] − (L = CH 3 CN or tetrahydrofuran (THF)), which was converted to [(PNP)CrCl 2 L 2 ] + [B(C 6 F 5 ) 4 ] − , where PNP is iPrN(PPh 2 ) 2 ( 1 ) or [CH 3 (CH 2 ) 16 ] 2 CHN(PPh 2 ) 2 ( 2 ). The molecular structures of [(THF) 4 Cr III Cl 2 ] + [B(C 6 F 5 ) 4 ] − and [ 1 -CrCl 2 (THF) 2 ] + [B(C 6 F 5 ) 4 ] − were unambiguously determined by X-ray crystallography. The cationic (PNP)Cr III complexes paired with [B(C 6 F 5 ) 4 ] − anions, that is, [(PNP)CrCl 2 (CH 3 CN) 2 ] + [B(C 6 F 5 ) 4 ] − , exhibited high activity in chlorobenzene when activated with common trialkylaluminum species (Me 3 Al, Et 3 Al, and iBu 3 Al). The activities and selectivity were comparable to those of the original MAO-based Sasol system ( 1 -CrCl 3 /MAO). When activated with Et 3 Al or iBu 3 Al, the Cr complex, [ 2 -CrCl 2 (CH 3 CN) 2 ] + [B(C 6 F 5 ) ...

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