成果報告書詳細
管理番号20110000000987
タイトル*平成22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 有機薄膜太陽電池モジュール創製に関する研究開発(新構造モジュールの研究開発)
公開日2011/10/12
報告書年度2010 - 2010
委託先名株式会社東芝
プロジェクト番号P07015
部署名新エネルギー部
和文要約 2030年までに太陽光発電量を53 GWとする我が国の導入目標を実現するために、安価で資源制約の少ない有機薄膜太陽電池(OPV)モジュールの製造のための光電変換組成物とモジュール製造の要素技術に関する研究開発を行う。これにより、セル効率12%およびモジュール効率10%を世界にさきがけ実現するものである。当事業では新型モジュールの開発をおこなう。当事業では新型モジュールの研究開発をおこなう。
1.セル材料の開発
セル・モジュールの特性を向上すべく、活性層材料(P 型、N 型)、中間層材料(TiOx、Ca、LiF、PEDOT:PSS)、電極材料、封止材料、基板材料などを開発にした。特に、P型材料としてPCDTBT、PTB7及び独自設計ポリマーを、N 型材料としてフラーレン(C70)誘導体を検討した。これらのうち最も高い変換効率を与えたのは、ITO/PEDOT:PSS/PTB7:PC70BM/Ca/Al の組合せであった。これにより微小平面セル効率6.4%の効率を得た。
2. 塗布印刷技術の開発
膜厚が100nm 前後の均一な膜を大面積に効率良く形成する塗布技術を確立すべく、塗布装置の設計・製作を行った。既に原理検証を終えた技術(液体のメニスカス力を利用する塗布方法)をベースに、塗液供給や基板移動、基板温度、雰囲気などの自動制御が可能で、最大塗布サイズ20cm 角の装置を組み上げた。
3.セル構造の開発
光電変換層の膜厚を増すことなく光吸収率を向上すると共に、入射光をセル内に閉じ込めることが可能な立体セル構造(傾斜セル)の可能性を検証した。セルを入射光に対して傾斜させることによって活性層内部の光路長の増加、ひいては光吸収の増大を実現するものである。光閉込効果と集光効果が相まって見かけ上の変換効率が谷底に近づくほど上昇する傾向を計算と実験の両面から確認した。またモジュール開発の中間目標(変換効率6%、30cm 角)の達成へ向け、平面及び傾斜サブモジュールを試作した。
英文要約Title: New Energy Technology Development, High Performance Photovoltaic System Development for the Next Generation, Research and Development for the Creation of Organic and Thin Film Solar Cell Module, Research and Development for New Structure Module (FY2010-FY2012) FY2010 Annual Report
The bulk-hetero-junction polymer solar cell seems to be promising, but their power conversion efficiency (PCE) is still too low for practical use. This problem is mainly caused by poor light absorption of the photo-conversion layer. As a solution, we had an idea of sloped cell architecture, which leads to a longer optical path through the active layer under inclined incident light and to a higher absorption. In basic research work, we confirmed that the sloped cells give higher PCE and the V-shaped multi-slope cells bring further advantages by its light trapping and concentrating effects. In this fiscal year, we tried to develop larger sloped cells and modules. First, we fabricated improved small cells, and had a PCE value of 6.4% for the planar small cell with the area of 0.1cm2. The materials and structure of this cell were as follows; Glass/ITO/PEDOT:PSS/PTB7:PC70BM/Ca/ Al. The V-shaped small sloped cell with the slope angle of 80 degrees and the area of 0.2cm times 1cm gave PCE of 10.3%. Next, we fabricated the planar and the multi-slope cells with the area of 1cm2. The results were 5.36% in the planar cell and 7.12% in the multi-slope cell with the slope angle of 80 degrees. The PCE values comparable to those of small cells are expected to be attained by improvements of materials and processes, and by minimization of the cell-area losses at the top and bottom portions in the W-shaped multi-slope cell. The sub-modules and modules were also fabricated. The 10cm2 sub-module consisting of sloped cells gave a power generation of 1.6 times larger than that of the planar sub-module with the same area, under illumination of 100mW/cm2. This result gave a solid evidence for the superiority of the sloped cell architecture. Further, we developed a 30 cm2 sub-module consisting of flexible substrate. After forming the organic and inorganic layers on a flexible PEN (polyethylene naphthalate) substrate, a multi-slope sub-module was fabricated by folding it. This sub-module worked stably during the exhibition period for two days, which shows the possibility for low cost manufacturing of the multi-slope cell. A slope module with the area of 20cm square is currently under fabrication. We also worked on the development of materials for the active layer, the intermediate layers, the electrodes, the sealing layer and the substrate. Among the materials we developed for the donor in the active layer, PTB7 showed the best performance. Improvements of this material and developments of original materials are in progress. A coating machine was designed and constructed to form the active and intermediate layers automatically on the area of 20cm square. By a life test of the planar cell under continuous 1-sun illumination for 500 hours, relative efficiency degradation less than 6.4% was observed. The technique for the PCE measurement in sloped cell and the simulators for the photoelectric conversion processes were also developed.
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