Journal of the Physical Society of Japan, Dec 15, 2001
Temperature variation of the crystal structure has been investigated for Tb 2 Ba 2 Co 4 O 11 , wh... more Temperature variation of the crystal structure has been investigated for Tb 2 Ba 2 Co 4 O 11 , which shows a metal-insulator (MI) transition at T MI = 340 K. The compound has a layered-type double-perovskite structure along the c -axis, with alternating the CoO 6 octahedron and the CoO 5 pyramids along the a -axis. With decrease of temperature below T MI , the distortion of the octahedral and pyramidal sites is fairly released, suggesting that spin state transition of the Co 3+ ions is the origin for the MI transition.
Journal of the Physical Society of Japan, May 1, 2003
2 p , c, and of Tb1 xCaxMnO3 (0:5 x 1:0) against Ca concentration x at 10K. The powder patterns f... more 2 p , c, and of Tb1 xCaxMnO3 (0:5 x 1:0) against Ca concentration x at 10K. The powder patterns for the lower and higher x-range can be well reproduced by the single orthorhombic (Pnma: open symbols) model. In the concentration range of 0:65 x 0:85, however, the powder patterns were reproduced by the twophase model with orthorhombic and monoclinic (P21=m: filled symbols) phases. Note that the room temperature structure was the single-phase even in this x region. The lattice constants, a, b= ffiffiffi
ABSTRACT Charge formation on the donor--acceptor (D--A) interface is the key process in organic p... more ABSTRACT Charge formation on the donor--acceptor (D--A) interface is the key process in organic photovoltaics (OPVs). Here, we experimentally demonstrated that the charge formation dynamics in the hexabenzocoronene (HBC)--C60 dyad system crucially depends on the structure of the D--A interface. In the self-assembled (SA) film with well-defined tube-type interface, we observed a conversion process from the donor HBC exciton (D*) to the donor charge (D+). Reflecting the two-dimensional (2D) shape of the respective domains, the charge formation time (τrise = 7.9 ps) in the SA film is much slower than τrise (≤ 1 ps) in the nonassembled (NA) film.
ABSTRACT The nanolevel molecular structure of a bulk heterojunction (BHJ) with a donor (D) polyme... more ABSTRACT The nanolevel molecular structure of a bulk heterojunction (BHJ) with a donor (D) polymer and acceptor (A) fullerene derivative is indispensable for true comprehension of highly efficient organic photovoltaic devices. Here, we performed scanning transmission X-ray microscopy of a poly(9,9-dioctylfluorene-co-bithiophene) (F8T2)/[6,6]-phenyl C71-butyric acid methyl ester (PC71BM) blend film with periodic nanostructure. The spatially resolved carbon K-edge absorption spectra revealed that the nanostructure consists of two types of domains with considerable molecular mixing. The fullerene mass fraction is 71 ± 1 and 33 ± 2 wt % for the PC71BM- and F8T2-rich domains, respectively.
Journal of the Physical Society of Japan, Jul 15, 2003
Density nHS of photoexcited high-spin (HS) sites in a spin-crossover film (Nafion-[Fe(Htrz)3]; Ht... more Density nHS of photoexcited high-spin (HS) sites in a spin-crossover film (Nafion-[Fe(Htrz)3]; Htrz = 1,2,4-4H-triazole) was systematically investigated against temperature T and excitation power density P. At low temperatures (<=35 K), the nHS-P curve shows a nonlinear increase when P reaches a critical value (Pc). We interpreted the increase in terms of the dynamical phase transition into the condensed state of photoexcited HS molecules, and derived the P-T phase diagram. The P-T phase diagram and the nHS-P curves were analyzed with an Ising-like model which includes a temperature-dependent field.
Journal of the Physical Society of Japan, Dec 15, 2001
Temperature variation of the crystal structure has been investigated for Tb 2 Ba 2 Co 4 O 11 , wh... more Temperature variation of the crystal structure has been investigated for Tb 2 Ba 2 Co 4 O 11 , which shows a metal-insulator (MI) transition at T MI = 340 K. The compound has a layered-type double-perovskite structure along the c -axis, with alternating the CoO 6 octahedron and the CoO 5 pyramids along the a -axis. With decrease of temperature below T MI , the distortion of the octahedral and pyramidal sites is fairly released, suggesting that spin state transition of the Co 3+ ions is the origin for the MI transition.
Journal of the Physical Society of Japan, May 1, 2003
2 p , c, and of Tb1 xCaxMnO3 (0:5 x 1:0) against Ca concentration x at 10K. The powder patterns f... more 2 p , c, and of Tb1 xCaxMnO3 (0:5 x 1:0) against Ca concentration x at 10K. The powder patterns for the lower and higher x-range can be well reproduced by the single orthorhombic (Pnma: open symbols) model. In the concentration range of 0:65 x 0:85, however, the powder patterns were reproduced by the twophase model with orthorhombic and monoclinic (P21=m: filled symbols) phases. Note that the room temperature structure was the single-phase even in this x region. The lattice constants, a, b= ffiffiffi
ABSTRACT Charge formation on the donor--acceptor (D--A) interface is the key process in organic p... more ABSTRACT Charge formation on the donor--acceptor (D--A) interface is the key process in organic photovoltaics (OPVs). Here, we experimentally demonstrated that the charge formation dynamics in the hexabenzocoronene (HBC)--C60 dyad system crucially depends on the structure of the D--A interface. In the self-assembled (SA) film with well-defined tube-type interface, we observed a conversion process from the donor HBC exciton (D*) to the donor charge (D+). Reflecting the two-dimensional (2D) shape of the respective domains, the charge formation time (τrise = 7.9 ps) in the SA film is much slower than τrise (≤ 1 ps) in the nonassembled (NA) film.
ABSTRACT The nanolevel molecular structure of a bulk heterojunction (BHJ) with a donor (D) polyme... more ABSTRACT The nanolevel molecular structure of a bulk heterojunction (BHJ) with a donor (D) polymer and acceptor (A) fullerene derivative is indispensable for true comprehension of highly efficient organic photovoltaic devices. Here, we performed scanning transmission X-ray microscopy of a poly(9,9-dioctylfluorene-co-bithiophene) (F8T2)/[6,6]-phenyl C71-butyric acid methyl ester (PC71BM) blend film with periodic nanostructure. The spatially resolved carbon K-edge absorption spectra revealed that the nanostructure consists of two types of domains with considerable molecular mixing. The fullerene mass fraction is 71 ± 1 and 33 ± 2 wt % for the PC71BM- and F8T2-rich domains, respectively.
Journal of the Physical Society of Japan, Jul 15, 2003
Density nHS of photoexcited high-spin (HS) sites in a spin-crossover film (Nafion-[Fe(Htrz)3]; Ht... more Density nHS of photoexcited high-spin (HS) sites in a spin-crossover film (Nafion-[Fe(Htrz)3]; Htrz = 1,2,4-4H-triazole) was systematically investigated against temperature T and excitation power density P. At low temperatures (<=35 K), the nHS-P curve shows a nonlinear increase when P reaches a critical value (Pc). We interpreted the increase in terms of the dynamical phase transition into the condensed state of photoexcited HS molecules, and derived the P-T phase diagram. The P-T phase diagram and the nHS-P curves were analyzed with an Ising-like model which includes a temperature-dependent field.
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Papers by Yutaka Moritomo