成果報告書詳細
管理番号20120000000159
タイトル*平成23年度中間年報 新エネルギー技術研究開発 革新的太陽光発電技術研究開発(革新型太陽電池国際研究拠点整備事業)高度秩序構造を有する薄膜多接合太陽電池の研究開発(ナロー/ワイドギャップ、高性能透明導電膜、有機単結晶)
公開日2012/11/30
報告書年度2011 - 2011
委託先名東京工業大学
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: Development of epitaxial growth of single crystalline Ge and related thin films (FY2008-FY2012) FY2011 annual report


For the optimum condition of the film growth, we changed the growth parameters of substrate temperature, gas flow ratio, pressure and evaluated the growth rate, Ge content, surface morphology, RMs value of the films: in thecondition of Si2H6/GeF4=15/3 and Pr=5torr, the deposition rate and Si-content were increased when the substrate temperature was increased; in the condition of Si2H6/GeF4=15/2 and substrate temperature of 350℃, Ge-content, crystallinity, deposition rate, and RMS value were improved when the gas pressure was increased from 0.5 to 8Torr; in the condition of Pr=5torr and the substrate temperature of 350℃, Ge-content and crystallinity of the films were decreased when the gas flow ratio was increased from 1.5 to 10, while the deposition rate and RMS value had the optimum gas flow ratio of a and 5, respectively. According to these results, we set the optimum condition of Si2H6/GeF4=2.0, Ts= 350℃, and Pr= 8.0torr, and obtained Ge films having the RMS value of 4.73nm and Ge-content of 99.1% at the deposition rate of 0.6nm/s, This film exhibited a very low etch pit density of ~2×105cm-2. 


In this work, the crystal growth and electric properties of ITO (indium tin oxide) thin films on our originally developed nanoimprinted-glass substrates were investigated in order to fabricate the high-performance transparent conducting oxide thin films for the organic molecule-based thin film solar cell. We examined the conditions for the development of atomically ultrasmooth surfaces on commercial silicate glass substrates by the thermal nanoimprint technique using α-Al2O3 single crystal molds with 0.2 nm-high atomic steps. As a result, 0.2 nm-high stepped and an atomically ultrasmooth terraced surface could be formed on soda-lime silicate glass substrates. The ultrasmooth surface morphology of the ITO thin film reflected the atomically stepped pattern of the glass substrate surface.


We have developed a new IR-laser deposition system specially designed for the growth of single crystalline organic charge-transfer (CT) complexes with ionic liquids (ILs). In this system, it has become possible to independently control the deposition of two organic molecular components in the organic CT complex by using two IR lasers.Secondary, we have tried to fabricate organic solar cells using p-type hybrid compounds of pentacene & Cu-phthalocyanine single crystalline films grown by IL-assisted vacuum deposition on ITO, combined with n-type PCBM. The value of Jsc in the solar cell became twice, thereby the total efficiency did twice as compared to those fabricated without using IL. However, it is still a serious problem that the remained IL acts as a recombination center to considerably degrade the efficiency in the separation of electron-hole pairs.


Cu2O was selected as the most promising candidate for p-type layer in all-oxide-based solar cell. The post-annealing at 400°C after room-temperature deposition by PLD method was effective for fabricate highly oriented and high mobility Cu2O thin films, whose mobility reach ~13 cm2/Vs. However, electrical and optical properties were highly affected by film thickness. Photocurrent and optical absorption spectra suggest that metallic Cu or CuO exists in the films and it forms the dead layer. As a result, the a-IGZO/Cu2O solar cell showed low JSC and large leakage current. Further optimization of the preparation conditions is required for fabricating solar cells with high JSC and low leakage current.
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