成果報告書詳細
管理番号20110000000439
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(薄膜新素材)
公開日2011/7/28
報告書年度2010 - 2010
委託先名岐阜大学
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 サブテーマ1-5 薄膜新素材 本テーマの薄膜新素材では、4~5セルで構成される薄膜フルスペクトル太陽電池の高効率化で必要となる各セルの禁制帯幅の太陽光スペクトルへのマッチングにおいて、より最適な禁制帯幅を有する光電変換材料を利用可能とするため、広範囲に禁制帯幅を可変できる新材料の開発を目的として、(1)アモルファス/微結晶InGaN系薄膜材料の開発と(2)ゲストフリーSiGe系クラスレート薄膜における禁制帯幅制御技術の開発を行い、それらの太陽電池形成技術の確立を行う。
英文要約Title: Development of Novel Si Based and Amorphous Alloy Thin Films (FY2008-FY2010) FY2010 Annual Report
A flexibility of optical band gaps is important issue to achieve thin film multi-junction solar cells with conversion efficiency over 40 %. In this project, InXGa1-XN alloys and Si based clathrate compounds are developed because of the applicability as new thin film materials for photo-absorpbing layers with the band gap energy of 2-2.5 eV and 1.2-2 eV, respectively.
- Amorphous Alloys Thin Films: InXGa1-XN - Depositions of InXGa1-XN films were carried out using GaN and InN targets instead of Ga and In targets by sputtering method. The N composition in the films deposited using GaN and InN targets was larger than that deposited using Ga and In metal targets. The photosensitivity of 252 was obtained in the In0.35Ga0.65N film with the optical band gap energy of 2.1 eV and was much larger than that (1.89) in the film deposited using Ga and In targets. We have developed the improving method of the photosensitivity in InXGa1-XN films. The trial production of InXGa1-XN solar cells (Asahi-U type substrate/p-type a-Si1-yCy:H/i-type a-Si:H buffer/In0.35/Ga0.65N/In0.41Ga0.59N) were carried out. In the solar cell, the efficiency of 1.1 %, open circuit voltage of 0.52 V, short current density of 5.64 mA/cm2, and fill factor of 0.38 were obtained. We also succeeded the trial production of InXGa1-XN solar cell.
- Novel Si Based Thin Films: Si clathrate - To establish high yield synthesis of guest free type II Si clathrate, a preliminary thermal annealing at 250 C under vacuum were examined before annealing at 450 C which is the main process to synthesize the Si clathrate from NaSi zintl phase. The pre-annealing for 50 hour resulted in the large amount of type II Si clathrate (NaxSi136) with x less than 3. The mass fraction of NaxSi136 was higher than 80 %. The purity of NaxSi136 was further improved to 90 % or higher by a centrifugation method using an appropriate fluid-mixture (CH2Br2-C2Cl4) with density of 2.1-2.2 g/ml. The optical band gap of the purified NaxSi136 with x = 1.0 and 2.2 was estimated to 1.8 eV with the aid of photo-acoustic spectroscopy. The photoconductivity was also measured under vacuum using a Xe lamp, and consequently observed with a photosensitivity of 1.1. In order to obtain Kr doped Si clathrate with film structures, KrSi film was deposited using rf-sputtering with a mixture of krypton and hydrogen gases. According to EDX analysis, the atomic ratio of Kr and Si compositions (Kr/Si) increased up to 20% as the Kr gas pressure increased. The Kr/Si is higher than that of the fully Kr doped Type II Si clathrate (Kr24Si136 : Kr/Si = 17.6%). The KrSi film was annealed at 350 C for 4 hrs. The Kr was almost effused with annealing pressure under 1 atm. When the film was annealed at 148 bar using a pressure vessel, the Kr in KrSi films could be kept at 50% after annealing. However, the X-ray diffraction of annealed films did not correspond to that of Si clathrate.
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