- 著者
- Yonezawa Kouhei Kamioka Hayato Yasuda Takeshi Han Liyuan Moritomo Yutaka
- 出版者
- American Institute of Physics
- 雑誌
- Applied physics letters (ISSN:00036951)
- 巻号頁・発行日
- vol.103, no.17, pp.173901, 2013-10
- 被引用文献数
- 9 1
By means of femto-second time-resolved spectroscopy, we investigated the carrier formation process against film morphology and temperature (T) in highly-efficient organic photovoltaic, poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5- ] dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b] thiophenediyl]] (PTB7)/[6,6]-phenyl -butyric acid methyl ester solar cells. We found that the carrier formation efficiency ( ) from an absorbed photon is nearly independent of the film morphology, indicating that the internal quantum efficiency ( ) is mainly governed by the carrier transfer efficiency ( ) to the electrodes. The activation energy ( ) of is significantly low, which suggests an extended charge-transfer state around the PTB7/PC70BM interface.
- 著者
- Akaba Takahiro Yonezawa Kouhei Kamioka Hayato Yasuda Takeshi Han Liyuan Moritomo Yutaka
- 出版者
- American Institute of Physics
- 雑誌
- Applied physics letters (ISSN:00036951)
- 巻号頁・発行日
- vol.102, no.13, pp.133901, 2013-04
- 被引用文献数
- 11
We investigated carrier formation dynamics in a small-molecular bulk heterojunction solar cell, 2,5-di-(2-ethylhexyl)-3,6-bis-(5″-n-hexy-[2,2′,5′,2″]terthiophen-5-yl)-pyrrolo[3,4-c]pyrrolo-1,4-dione/[6,6]-phenyl C71-butyric acid methyl ester, with low bandgap (Egap ≈ 1.5 eV). The photoinduced absorption (PIA) spectra of the blend film were decomposed into three PIAs, i.e., those due to donor exciton (D*), acceptor exciton (A*), and mobile carrier (D+). The analysis revealed carrier conversion from D* with a conversion time of ∼1.3 ps.
- 著者
- Kamioka Hayato Hirano Masahiro Hosono Hideo
- 出版者
- American Institute of Physics
- 雑誌
- Journal of applied physics (ISSN:00218979)
- 巻号頁・発行日
- vol.106, no.5, pp.053105, 2009-09
- 被引用文献数
- 12
Eu2+ doped sorosilicate Ca2ZnSi2O7 (melilite) exhibits a broad band emission peaking at ~600 nm (~2 eV) due to the electric dipole allowed transition of 4f65d1 to 4f7 of Eu2+ by an excitation with blue light (460 nm). Strong O2− ligand field with low symmetry due to the layered tetragonal crystallographic structure of the melilite may play a dominant role in lowering the emission band energy to ~2 eV. In addition, line emissions attributable to the transitions from 5D0 to 7FJ of Eu3+ ions are detected by an excitation with deep UV light with sub-360 nm wavelengths. This is due to the formation of transient Eu3+ ions via charge transfer from Eu2+ to the matrix. The lifetime of the transient Eu3+ ion is found to be 58 ms by a pump-probe measurement, in which UV pulse laser and green continuous wave laser are employed as pump and probe lights, respectively. Based on these results, the energy diagram of Eu2+ in Ca2ZnSi2O7 is proposed.