成果報告書詳細
管理番号20130000000559
タイトル*平成24年度中間年報 太陽エネルギー技術研究開発 太陽光発電システム次世代高性能技術の開発 フィルム型軽量低価格色素増感太陽電池の研究開発(高性能色素及び電極の研究開発とセル性能総合評価)
公開日2015/4/25
報告書年度2012 - 2012
委託先名国立大学法人山形大学
プロジェクト番号P07015
部署名新エネルギー部
和文要約
英文要約Title: R&D of PV Technology. R&D for Next Generation High Performance PV Systems. R&D of Plastic Film Type Light-weight Low-cost Dye-sensitized Solar Cell. R&D of Plastic Film Type DSC Module. (FY2010-2013)
FY2012 Annual Report

(1) As the sight of the R&D moved from Gifu Univ. to YU, the instruments were moved and re-installed in YU. The system was re-boot and refined especially for having the same standards with GUNZE, for the cells employing ITO films to assure the feedback of the technologies for efficiency improvement. While the reference cells employing FTO glass substrate, electrodeposited ZnO and D149 dye achieved a slightly improved efficiencies ranging between 5.0 and 5.4% as compared to the previous standard of 5.1% in GU, the new reference film cells employing ITO film, screen-printed ZnO and DN291 achieved 3.4%. DN291 is the new reference dye developed in this project, achieving a slightly lower efficiency than D149 but with a much higher stability.
(2) Even though electrodeposited ZnO has a superior performance to the printed particulate ZnO, its high adherence imposes a high strain to ITO to peal it off the base polyester film. In order to overcome this problem, rhodamine B, having a high interfacial activity, was used as the structure directing agent (SDA) and achieved a well adherent regularly porous ZnO on ITO films.
Since GUNZE is going to focus on the printing technique and also because of the discovery of combination of D35 dye and Co(II/III) redox electrolyte for achieving over 1 V voltage, methods to synthesize highly crystallized, structure and size controlled ZnO have been developed. When aqueous zinc acetate solution containing triethanolamine as SDA was heated for 30 min at 150⁰C by microwave, highly crystallized idiomorphic ZnO particles could be obtained. The size of the particles could be controlled between 20 and 100 nm by changing the pH of the precursor solution.
(3) New narrow gap dye, DN350, was employed to the film DSC and achieved 4.44% as compared to 3.43% of the DN291 cell. DN350 has a narrower energy gap (2.03 eV) than that (2.08 eV) of D149, and also positively shifted HOMO level (0.78 V vs. NHE as compared to 0.76 V of D149), so that it achieves facile regeneration to receive electron from iodide. While ca. 30 nm red shift of the onset wavelength is achieved, IPCE of DN350 was slightly higher than that of DN291, so that the short circuite current density increased from 8.7 to 10.6 mA cm-2.
(4) GUNZE found a combination of dyes to exhibit supersensitization specifically on ZnO photoelectrodes to achieve ca. 14 mA cm-2 short circuit photocurrent and achieved a 5.83% conversion efficiency, which are remarkably high for film-type DSCs employing stable components such as ionic liquid electrolyte. While this cell also achieves a high fill factor of 0.7, its voltage is rather low (ca. 0.6 V). Therefore, we have focused on technologies to increase voltage of ZnO solar cells. For iodide redox system, several additives to the electrolyte solution were tested for ZnO/D149 solar cells. Among them, octanoic acid was found to extend the electron lifetime while causing positive shift of the conduction band as checked by SLIM-PCV measurements. As a consequence, it achieved an increase of open circuit voltage from 629 to 661 mV without changing the current, so that the efficiency increased from 3.85 to 4.12%. Aiming a significant increase of the voltage, use of Co(II/III) complex redox couple having more positive potential than iodide redox was studied. Kinetically reversible Co redox requires dense dye layer to suppress back electron transfer to Co(III). Among various dyes studied, D35 dye (Dyenamo) specifically exhibited a high voltage over 1 V. By combining the strategies to improve current and voltage, over 10% efficiency can be envisaged and that will be the task for the next FY.
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