The 277th MANA & the 118th ICYS Joint Seminar
Dr. Ryoma Hayakawa & Dr. Xudong Yang
| Date | July 20, Friday |
| Time | 15:30-16:30 |
| Place | Auditorium, 1F, WPI - MANA Bldg., NAMIKI Site, NIMS |
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15:30-16:00
Optically- and electrically-driven dual-gate transistor with diarylethene photochromic channel layers
Organic electronic devices have attracted considerable attention for realizing printable and flexible logic circuits. In the last decade, great progress has been made as regards the performance of organic field-effect transistors (OFETs). The development of novel OFETs with specific functionality is attracting attention with a view to providing a new direction for organic electronics.
In this talk, I will present optical manipulation of the drain current in OFETs with diarylethene channel layers. The drain current was reversibly changed by alternating UV and VIS light irradiation. Importantly, the on/off ratio realized by light irradiation was 102 and this value is comparable to that induced by gate voltage. The result indicated that the drain current was manipulated by two gates, namely, optical and electrical gates. Our finding demonstrates the potential to achieve high-performance opto-electrical organic devices including optical sensors, optical memory and photoswitching transistors.
Speaker
Dr. Ryoma Hayakawa, MANA Independent Scientist, MANA, NIMS
Chair
Dr. Yutaka Wakayama, MANA Scientist, MANA, NIMS
16:00-16:30
Interfacial Interactions in High Efficiency Dye-sensitized Solar Cells
Dye-sensitized solar cells (DSCs) have attracted great interests as potential candidates of “low cost solar cells” in the solution of global energy demand. It is highly desirable to improve the energy conversion efficiency of DSCs for commercial application by increasing the open-circuit voltage (VOC) and short-circuit photocurrent (JSC). However, the efforts for high efficiency DSCs have met a dilemma that a significant increase in VOC is always accompanied by a decrease in JSC and vice versa, in which the underlying mechanism is still not clear. Here, we demonstrate how the interfacial interactions influence the VOC and JSC in high efficiency DSCs. Our findings indicate that the quasi-Fermi-Level of TiO2 electrode is dependent on the interactions between TiO2 and additives in electrolyte. Moreover the interactions between dye molecules and additives have significant effects on the photo induced charge generation, transfer and recombination. The present work can provide a deeper understanding of the fundamental mechanism in DSCs for further improvement of the energy conversion efficiency.
Speaker
Dr. Xudong Yang , ICYS=Sengen Researcher, NIMS
Chair
Dr. Kenjiro Miyano, Managing Director, ICYS, NIMS