成果報告書詳細
管理番号20120000000819
タイトル*平成23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 CIS系薄膜太陽電池の高効率化技術の研究開発
公開日2013/10/31
報告書年度2011 - 2011
委託先名昭和シェル石油株式会社
プロジェクト番号P07015
部署名新エネルギー部
和文要約光吸収層の高品質化技術開発に関して、硫化プロセスの改良により結晶粒径の拡大・キャリア収集の増大を確認し、Voc×Jsc=24mW/cm2が得られる技術を確立した。デバイス設計の改善技術開発に関して、デッドエリア低減によるJsc向上と合わせてサーキットデザインの最適化を実施した結果、FFの中間目標0.73を達成した。以上により、30cm角サブモジュールで世界最高効率17.8%(自社測定、開口部面積819cm2)を達成した。
英文要約Title: Research and Development of High Efficiency CIS Thin-Film Solar Cells
(FY2010-FY2012) FY2011 Annual Report

Since we, Showa Shell Sekiyu K.K. had already achieved 17% of conversion efficiency, which was our intermediate target for FY2011, with a 30 x 30cm sized sub module in FY2010, we have been focusing on following five topics to achieve our final target, 18% of efficiency with a 30 x 30cm sized sub module in 2014, through this year.

(1) Quality Improvement of p-type CIS Absorber Layer to Enhance Voc×Jsc
We examined the sulfurization after selenization (SAS) process, which is our proprietary technology to form p-type CIS light-absorbing layer, in order to improve the quality (or Voc×Jsc) of the layer. To enhance Voc×Jsc, we made CIS light-absorbing layer thicken and modified the sulfurization process accordingly. With this modification, gain size and carrier collection are confirmed to become larger and smoother, respectively, resulting in development of technology to obtain Voc×Jsc=24mW/cm2.

(2) Formation of High Quality Junction Interface
We conducted a preliminary examination for developing high quality junction interface this fiscal year. Specifically, we explored possibility of several new buffer layers in which band structure is expected to fit the high quality light absorbing layer well. As the result, a new buffer layer, which has high potential to be better than conventional one, was found.

(3) Distribution Improvement on Substrates
We simply succeeded last year’s findings and applied the same technology to control elemental distribution of substrate. As we decided to focuses on the other topics, no particular new technology was developed this year regarding this topic.

(4) Device Design Improvement
We employed a new patterning machine, aiming to reduce dead area without increasing leak current level. Although we had already developed a technology to reduce leak current on patterning lines using our previous pattering machine last year, we were able to confirm that the same technology can be applicable with the new machine. In addition to the technology to reduce leak current, we optimized cell width and attempted to enhance Jsc by reducing dead area.
As the result, the cell width was successfully optimized without changing total dead area, resulting in achievement of interim FF target of 0.73.

(5) Improvement of Optical Design
We examined the technology of reducing refraction at the surface of module based on our last year’s result. Specifically, we have investigated on light trapping structure through texture optimization of transparent conductive oxidize (TCO) window layer.
It is obvious that both higher transparency and lower reflectivity are necessary to improve quality of TCO layer and enhance Jsc. We had been trying to improve quality of TCO layer by analyzing single layers of TCO deposited directory on glass substrates until last year. We have found, however, that the results of the single layers sometimes do not reflect the real nature of TCO layer on the CIS thin film. So, this year, we investigated and optimized TCO layer deposited on CIS layer. As the result, we successfully found a better TCO deposition parameter, which had been identified to deteriorate the transparency of TCO layer on glass substrates, and achieved improved Jsc by over 1%.

By combining these five research and development results, we have established technology to obtain Voc×Jsc=24mW/cm2, which is our final target of the project, and have developed world champion 30×30cm sized sub module with the efficiency of 17.8% (internal measurement, aperture area 819 cm2).
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