Mitsuharu Noto

Preparation of amphiphilic poly(thiophene)s and their application for the construction of organic–inorganic superlattices

Abstract We prepared three types of poly(thiophene)s having aminoalkyl substituents: poly(3-aminoethylthiophene), poly(3-aminododecylthiophene), and poly[2,5-(3-octadecylthiophene)-alt-2,5-(3-aminomethlthiophene)]. From the absorption spectra of the poly(thiophene) films, it was demonstrated that their mean π-conjugation length was shortened compared to poly(3-alkylthiophene) prepared by the same chemical way. When a spin-coated film of hydrogen bromide salt of poly(3-aminododecylthiophene) was soaked in aqueous solution of PbBr 2 , PbBr-based layered perovskite structure combined with a semiconductor layer of two-dimensional sheets of PbBr 6 octahedra and an organic semiconductor layer of poly(thiophene) was formed; sharp exciton absorption of approximately 400 nm, which is the characteristic of PbBr-based layered perovskite was observed.

Hole Mobility of Fluorene-Based Dyes

Abstract Four fluorene-based dyes were newly prepared and they were demonstrated to possess excellent hole-transporting capability from the conventional time-of-flight measurement. In particular, a fluorene-based dye with diphenylamino groups exhibited high mobility of 1.8 × 10−3 cm2V−1s−1, which is about twice that of typical hole conductor N,N′-diphenyl-N,N′-(m-tolyl)-benzidine (TPD), in vacuum-deposited film

Fluorene Derivatives with High Hole Mobility

Fluorene derivatives having electron-releasing carbazole and diphenylamino substituents were demonstrated to possess high hole mobility at the level of 10−3 cm2V−1sec−1 in their amorphous films from the time-of-flight measurement; for the fluorene derivative with carbazole substituent, μ = 3.1 × 10−3 cm2V−1sec−1 at an applied field of 1.6 × 105 Vcm−1.

Electroluminescent Device Using PbBr-Based Layered Perovskite Having Self-Organized Organic-Inorganic Quantum-Well Structure

PbBr-based layered perovskites exhibit sharp and intense exciton emission around 410 nm owing to their self-organized quantum-well structure. We prepared heterostructure electroluminescent devices combined with the PbBr-based layered perovskite as emissive material and organic carrier transporting materials: indium tin oxide (ITO) /PbBr-based layered perovskite (CHEPbBr4)/ electron-transporting oxadiazole (OXD7)/AlLi and ITO/Copper phthalocyanine (CuPc)/CHEPbBr4/OXD7/AlLi. When the devices were driven at 100K, sharp electroluminescence corresponding well to exciton emission of CHEPbBr4 was observed. Further, comparison between voltage-current density-EL intensity characteristics of the devices demonstrated that employment of CuPc layer as hole-injection and transporting layer provides large lowering driving voltage and enhancement of EL efficiency of the heterostructure EL device.

Red electroluminescence from divalent europium iodide nano-particle doped in organic-semiconductor

Abstract A hybrid film embedded with EuI 2 nano-particles was successfully prepared by simultaneous vacuum-deposition of an organic semiconductor, 4,4′- N , N ′-dicarbazole-biphenyl (CBP), and EuI 2 . TEM image exhibited EuI 2 formed spherical particles with diameters ranging approximately from 9 to 14 nm in the hybrid film. We fabricated a three-layer EL device using the hybrid film as emissive layer. The device emitted red emission due to 4f 6 5d 1 →4f 7 transition of Eu 2+ . The device exhibited maximum luminance and maximum external quantum efficiency of 377 cd/m 2 at 362 mA/cm 2 and 0.18% at 14.5 cd/m 2 at 7.12 mA/cm 2 , respectively.

Blue EL Devices with Arylethynylbenzene Derivatives as Emissive Materials

Abstract New arylethylbenzene derivatives were prepared as emissive material for organic electroluminescent (EL) device. In the EL device using an arylethynylbenzene with naphthyl group, intense blue emission was successfully observed; emission was peaking at 450 nm, and maximum luminance was 788 cdm−2 at a current density of 3.05 Acm−2