Search

Your search keyword '"Fujii, Akihiko"' showing total 789 results
Start Over Author "Fujii, Akihiko"
789 results on '"Fujii, Akihiko"'

4. Dynamics of Self-Gravity Wakes in Dense Planetary Rings I. Pitch Angle

Author

Michikoshi, Shugo, Fujii, Akihiko, Kokubo, Eiichiro, and Salo, Heikki

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We investigate the dynamics of self-gravity wakes in dense planetary rings. In particular, we examine how the pitch angle of self-gravity wakes depend on ring parameters using N-body simulations. We calculate the pitch angles using the two-dimensional autocorrelation function of the ring surface density. We obtain the pitch angles for the inner and outer parts of the autocorrelation function separately. We confirm that the pitch angles are 15 to 30 degrees for reasonable ring parameters, which are consistent with previous studies. We find that the inner pitch angle increases with the Saturnicentric distance, while it barely depends on the optical depth and the restitution coefficient of ring particles. The increase of the inner pitch angle with the Saturnicentric distance is consistent with the observations of the A ring. The outer pitch angle does not have the clear dependence on any ring parameters and is about 10 - 15 degrees. This value is consistent with the pitch angle of spiral arms in collisionless systems., Comment: 30 pages, 14 figures, accepted for publication in ApJ

Published
2015
Full Text
View/download PDF

14. Sandwich-cell-type organic solar cellutilizing columnar liquid crystalline semiconductor

Author

Fujii, Akihiko, Nakata, Yuya, and Ozaki, Masanori

Subjects
有機半導体, 太陽電池, フタロシアニン, サンドイッチセル, 液晶
Abstract

Sandwich-cell-type organic solar cells utilizing a columnar liquid crystalline (Col LC) phthalocyanine, 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2), which is an organic semiconductor demonstrating high carrier mobility, as an active layer, were fabricated and their photovoltaic properties were studied. At 110℃ in the crystal phase, the highest power conversion efficiency of 1.24% was exhibited, that was strongly related with the enhanced carrier mobility. The stable performance of the solar cells was also demonstrated in the Col LC phase. The photovoltaic properties were discussed by clarifying the relationship between the column axis direction and carrier mobility in the active layer.

Published
2021

42. Fabrication, characterization and simulation analysis of perovskite solar cells with dopant-free solution-processible C6PcH2 hole transporting material.

Author

Dao, Quang-Duy, Gorji, Nima E., Alhodaib, Aiyeshah, Dinh, Thi-Ngoc, Fujii, Akihiko, Ozaki, Masanori, and Hajjiah, Ali

Subjects
PEROVSKITE analysis, CHARGE carrier mobility, OPEN-circuit voltage, ELECTRO-optical effects, QUANTUM efficiency, SHORT-circuit currents
Abstract

A new design of perovskite solar cells (PSCs) with non-peripherally substituted octahexylphthalocyanine (C6PcH2) hole transporting material (HTM) and MoOx buffer layer was introduced through experiment and simulation analysis. The external quantum efficiency (EQE) and current density–voltage (JV) characteristics were performed to analyze the photovoltaic performance of the PSCs based on C6PcH2 HTMs. The EQE was over 73% within the visible region (at 450 nm) but lower at 740 nm due to parasitic light absorption of C6PcH2 molecules. As a result, a short-circuit current density (Jsc) Jsc = 16.3 mA/cm2, open-circuit voltage (Voc) Voc = 0.95 V, fill factor (FF) FF = 35%, and a power conversion efficiency PCE = 5.4% were recorded under reverse bias scans (from open-circuit to short-circuit). Simulation analysis with Silvaco and SCAPS-1D was also performed to support the carrier transport analysis of PSCs with C6PcH2 HTM as well their photovoltaic performance in temperature range from 303 to 258 K, in which the charge carrier mobility of C6PcH2 molecules were strongly improved. By reducing the temperature from 303 to 258 K, the simulated PCE of 19.6% was achieved for the PSCs utilizing C6PcH2 as an HTM. The difference in PCEs between the synthesized and simulated devices was in part due to the alignment of C6PcH2 molecules in thin film. The simulation results closely supported the experiment and promised an improved performance upon realizing unknown electro-optical semiconductor properties of the C6PcH2 layer. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results