Publications by authors named "Koichi Tamaki"

Energy harvesting at low light intensities has recently attracted a great deal of attention of perovskite solar cells (PSCs) which are regarded as promising candidate for indoor application. Anomalous hysteresis of the PSCs a complex issue for reliable evaluation of the cell performance. In order to address these challenges, we constructed two new evaluation methods to determinate the power conversion efficiencies (PCEs) of PSCs.

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A high-temperature selected (HT) strain of rainbow trout was established from the Donaldson (DS) strain by traditional selective breeding in Japan. The aim of this study is to investigate genes related to upper temperature tolerance in this strain utilizing next generation sequencer (NGS), and to establish comprehensive and comparable datasets in brain, liver, muscle, heart and gill tissues between the HT and DS strains. After assembling, clustering and filtering, 242,530 contigs were obtained.

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Toward the extension of the light-harvesting region of sensitizers in dye-sensitized solar cells (DSSCs), two ethynyl-linked porphyrin trimers were synthesized and investigated. The zinc–freebase–zinc trimer (Zn–FbA–Zn) showed an absorption maximum at a longer wavelength than the all-zinc trimer (Zn–ZnA–Zn), although the energy level of Zn–FbA–Zn was lower than that of Zn–ZnA–Zn. The DSSCs using these trimers showed spectral sensitivities up to 900 nm.

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Ethynyl-linked porphyrin hetero-dimers substituted by a series of electron donors, namely, bis(4-methoxyphenyl)amino (BMPA), bis(4-tert-butylphenyl)amino (BTBPA) and 3,6-di-tert-butylcarbazol-9-yl (DTBC) as well as a reference dimer with a non-donor moiety (3,5-di-tert-butylphenyl, DTBP) have been synthesized to systematically investigate the influence of donor introduction on the photovoltaic performances of near-IR dye-sensitized solar cells (DSCs) with these sensitizers incorporated. Despite the expected bathochromic shift and intensification of long-wavelength absorption bands as well as elevated LUMO levels and thus increased electron injection driving forces, the substitution of diphenylamino groups (BMPA and BTBPA) with stronger electron-donating abilities gave rise to surprising mediocrity in the short-circuit photocurrent densities (J(sc)), leading to overall energy conversion efficiencies in the order BMPA (3.94%) < DTBP (4.

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N-fused carbazole-zinc porphyrin-free-base porphyrin triad featuring an ethynyl-linkage was synthesized; efficient sensitization as long as 900 nm was demonstrated and an overall light-to-electricity conversion efficiency of 5.21% was achieved under AM 1.5 G one sun illumination.

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A meso,meso-linked porphyrin dimer [(ZnP)(2)] as a light-harvesting chromophore has been incorporated into a photosynthetic multistep electron-transfer model for the first time, including ferrocene (Fc), as an electron donor and fullerene (C(60)) as an electron acceptor to construct the ferrocene-meso,meso-linked porphyrin dimer-fullerene system (Fc-(ZnP)(2)-C(60)). Photoirradiation of Fc-(ZnP)(2)-C(60) results in photoinduced electron transfer from the singlet excited state of the porphyrin dimer [(1)(ZnP)(2)] to the C(60) moiety to produce the porphyrin dimer radical cation-C(60) radical anion pair, Fc-(ZnP)(2)(*+)-C(60)(*-). In competition with the back electron transfer from C(60)(*-) to (ZnP)(2)(*+) to the ground state, an electron transfer from Fc to (ZnP)(2)(*+) occurs to give the final charge-separated (CS) state, that is, Fc(+)-(ZnP)(2)-C(60)(*-), which is detected as the transient absorption spectra by the laser flash photolysis.

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