成果報告書詳細
管理番号20110000000442
タイトル*平成22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)/低倍率集光型薄膜フルスペクトル太陽電池の研究開発
公開日2011/7/28
報告書年度2010 - 2010
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
和文要約和文要約等以下本編抜粋:1.研究開発の内容及び成果等 1.1研究開発の内容 「低倍率集光型薄膜フルスペクトル太陽電池の研究開発」では、大面積化が可能な薄膜系で、将来、エネルギー変換効率40%を実現するため、ワイドギャップからナローギャップの広い禁制帯幅の領域で、今までにない光吸収層材料を開発するとともに、広い波長範囲で有効にフォトンを利用するため光のマネージメント技術開発を行う。これらの要素技術をもとに、5~6接合からなる低倍率集光型薄膜太陽電池を試作し、エネルギー変換効率30%を達成する。
英文要約Title: Thin Film Full Spectrum Solar Cells with Low Concentration Ratios (FY2008-FY2010) FY2010 Annual Report, Tokyo Institute of Technology
In order to realize thin-film solar cells with conversion efficiencies over 40%, we are developing novel absorber materials. (1) Band gap Control of Nano Dots: The defect density of SiC/Si QDSL was reduced to the level of 1x1017/cm3 by optimizing atomic hydrogen treatment. For increasing the photocurrent of solar cells, a superstrate configuration was introduced. We successfully fabricated ITO/Si QDSL thin-film solar cells with a photocurrent of 5.4 mA/cm2. (2) Multi-Exciton: Fabrication process of P-I-N cell structure with silicon QDSL structures embedded in epitaxial CaF2 has been developed. Short-circuit current density of 0.01 - 1 mA/cm2 has been observed, which indicates feasibility and controllability of carrier transport and confinement of Si/CaF2 QD structure. (3) Bandgap Engineering of Strained Ge: The PL spectra of unstained Ge, 0.10% tensile-strained (TS) Ge, and 0.56% TS Ge were measured at 20K, and it was found that the indirect gap energy shifted to lower energy by increasing tensile strain for the first time. (4) Si Based Thin Film Concentrators: Theoretical and experimental studies were performed to explore the effect of light intensity on the performance of silicon-based thin film solar cells. The SiO/Si heterojunction is useful to increase the efficiencies of micorcystalline Si solar cells under concentrations. An efficiency of 9.4% was obtained under 9.44 suns for microcrystalline Si solar cell. Furthermore, efficiencies of 11.9% and 12.7% were achieved for a-Si/microcrystalline Si tandem solar cells for 1sun and 10suns, respectively. (5) Tomography analysis technique for the full spectrum solar cells: Two dimensional electroluminescence (EL) intensity in CIGS cells were analyzed in various injection current. In high injection, non-uniform distribution of EL was observed, which revealed the necessity of structure optimization. Different wavelength measurement will yield the investigation of tomography analysis. (6) Chalcopyrite based thin film concentrators: We have proposed a multi-stage process for the growth of high-quality Cu(InGa)Se2 with a high Ga content. An efficiency of 14.9% was achieved by the multi-stage process with a CIGS absorber whose band gap was 1.39eV. Ag(InGa)Se2 films were grown by the three-stage method, and an efficiency of 6.90% was obtained. The surface roughness of 1.5nm was realized by the chemical mechanical polishing (CMP) process to develop the direct bonding process for tandem-type solar cells. (7) Surface Plasmon: To apply surface plasmon effects to Si solar cells, thin polymer films containing metal nanoparticles were fabricated by a spin-coating method. The enhancement ratio of the conversion efficiency and the external quantum efficiency after spin-coating the film on a single-crystal Si solar cell was 12% and 22% respectively.
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