Masaya Kakimoto

Electroluminescent Diodes Utilizing Polysilanes

Electroluminescent (EL) diodes utilizing polysilanes have been fabricated, and their optical and electroluminescent characteristics have been investigated. We have succeeded in demonstrating electroluminescence from the ultraviolet region to the visible region using the EL diodes with thin polysilane films. The diode characteristics are discussed taking the polymer structure into consideration.

Synthesis of organosilanylene pentathienylene alternating polymers and their application to the hole-transporting materials in double-layer electroluminescent devices

Abstract Polymers composed of an alternating arrangement of organosilanylene and pentathienylene units, [SiBu 2 -X-SiBu 2 -(2,5-C 4 H 2 S) 5 ] n ( 1 : X=none, 2 : X=O) were prepared and their application to the hole-transport in double-layer electroluminescent (EL) devices was studied. The EL devices with the structure of ITO/ 1 or 2 /Alq/Mg:Ag emitted a green light resulting from Alq emission by applying the bias voltage. The device with 1 showed a lower turn-on voltage than that with 2 , while almost the same maximum luminance of 4000 cd m −2 was obtained from both of the devices.

Photoluminescence Quenching in Polysilanes by Fullerene Doping and Effective Photoinduced Charge Transfer Depending on Aromatic Side Group

Photoluminescence of polysilanes with aromatic side groups has been found to be strongly quenched upon C60 doping, in contrast to the case of polysilanes with saturated hydrocarbon side groups in which a clear quenching effect has not been observed. These results have been interpreted by considering the role of the aromatic side group as a mediator for photoinduced electron transfer from electronic states of the main chain polysilanes to the C60 molecule.

Effects of the ethoxy and diethylamino substituent on the electrochemical and conducting properties of poly[(silanylene)oligothienylenes]

Polymers composed of alternating ethoxypropyl- or diethylaminohexylsilanylene and oligo(2,5-thienylene) units, [(SiRX)(C4H2S)m]n (3a–5a, R=Pr, X=OEt, m=3–5; 5b, R=Hex, X=Et2N, m=5) were synthesized and their properties were investigated in comparison with those of the diethylsilanylene analogs, [(SiEt2)(C4H2S)m]n (3c–5c, m=3–5). The UV and emission bands, and anodic peaks in cyclic voltammograms of polymers 3a–5a and 5b are at almost the same energies as those of the respective 3c–5c with the same number of m. However, polymers 3a–5a and 5b were found to be much more stable toward electrochemical oxidation and reduction, as compared with 3c–5c with the same number of m. Polymers 3a–5a became conducting upon doping with FeCl3 with the conductivities in the order of 10−2–10−1 S cm−1, similar to the diethylsilanylene analogs 3c–5c. In contrast, polymer 5b exhibited highly conducting properties when doped with I2, whose conductivity was determined to be 4.4 S cm−1. Photoconducting properties of polymer 4a and 4c are also described.

Visible absorption of iodine‐doped polysilane with p‐N,N‐dialkylaminophenyl substituents

The doping effects on optical and electrical properties of polysilanes were investigated by in-situ measurement. When polysilanes bearing a p-N,N-dialkylaminophenyl substituent were doped with iodine vapor, drastic spectral changes were observed. The evolved visible absorption up to 700 nm was found to be strong and stable compared to that of iodine-doped polysilanes such as poly(methylphenylsilane). On the basis of the studies concerning iodine doping of the related p-N,N-dimethylaminophenyl-substituted silane and disilane, and also theoretical calculations, this new absorption can be best interpreted by the result of charge transfer consisting of the strong interaction between iodine and dialkylamino substituents in the polysilanes.

Ultraviolet electroluminescence and dye doping effect in conducting polymers

Abstract Electroluminescent (EL) diodes utilizing polysilanes have been fabricated and their optical and EL characteristics have been studied. We have succeeded in demonstrating electroluminescence in the ultraviolet and visible regions using the polysilane EL diodes. We have found that the EL efficiency has been enhanced in polysilane diodes doped with oxadiazole derivative compared with that in undoped polysilane diode