| Budget Amount *help |
¥18,630,000 (Direct Cost: ¥15,300,000、Indirect Cost: ¥3,330,000)
Fiscal Year 2007: ¥14,430,000 (Direct Cost: ¥11,100,000、Indirect Cost: ¥3,330,000)
Fiscal Year 2006: ¥4,200,000 (Direct Cost: ¥4,200,000)
|
|---|
| Research Abstract |
1. Synthesis of quantum dots (QDs)
CuInS_2 quantum dots with 〜5nm in size were successfully synthesized. The crystal structure of the CuInS_2 QDs, the chalcopyrite-type or the wurtzite-type, was dependent on the amount of the amines and the storage time after addition of amines. The optical absorption edges of the chalcopyrite- and wurtzite-types CuInS_2 QDs obtained were 〜710nm in wavelength. For the chalcopyrite-type CuInS_2, photoluminescence (PL) band at 930nm was observed, and no PL band was observed for the wurtzite-type CuInS_2. The PL band observed for the chalcopyrite-type QDs was attributed to the electron-hole recombination via defect revels. As a result of the further study of the starting solution, we successfully synthesized chalcopyrite-type CuInS_2 QDs with 1.5〜3nm sizes by controlling of the reaction time. For the CuInSe_2 QDs, the increase in PL intensity and the blue shift of the PL wavelength were observed by annealing in oleylamine at 200〜300℃. The changes in the PL properties were related to the increase in the crystallinity of the QDs.
2. Improving the PL properties
The PL band near optical absorption edge was newly appeared by overcoating of the CuInS_2 QDs by ZnS thin layer. The PL band may be attributable to the exciton recombination. In this experiment, the QDs used was 〜5nm in size. When the QDs with 2〜3nm in size are overcoated by ZnS, the blue PL may be realized.
3. Fabrication of the QDs thin films and electroluminescence devices
By using the ZnS-CuInS_2 alloyed QDs collidal solution as a starting solution, the QDs thin film on the glass substrate, which showed significant PL, was successfully fabricated by electro-spraying. We also fabricated the multilayered EL-device structure, such as glass/ITO/Al_2O_3/QDs-film/Al_2O_3/Al. However, we could not observe any electroluminescence from the device.
|
