成果報告書詳細
管理番号20130000000113
タイトル*平成24年度中間年報 太陽光発電システム次世代高性能技術の開発 フレキシブルCIGS太陽電池モジュールの高効率化研究 (電子構造評価によるデバイス特性向上技術の開発)
公開日2013/6/25
報告書年度2012 - 2012
委託先名国立大学法人鹿児島大学
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: The development of high performance flexible CIGS PV modules Development of key technologies for high-performance CIGS solar cells and modules based on characterization of their electronic structure (FY2010-FY2014) FY2012 Annual Report

1. Objectives: Electronic structures at interfaces and electronic activity of grain boundaries are to be investigated for developing key technologies for higher conversion efficiency in CIGS based flexible modules. Correlations between these characteristics and fabrication parameters and guiding principle for process-optimization are to be clarified.
2. For FY 2012
(1) Clarification of electronic structure of Cu-Se compounds
Electronic structure of Cu2Se and CuSe compounds are characterized by PES/IPES, since it is suggested in this R&D project that Cu-Se compounds are potential recombination centers especially in wide band gap CIGS absorbers. Cu2Se shows clear Fermi-edge. Gap like structure with a width of 0.8 eV is located at 3 eV above Fermi level. These results reveal Cu2Se is degenerated semiconductor by hole-doping. Contrarily to an expectation that excessive introduction of Cu-vacancies into Cu2Se might result in creation of bivalent state of Cu ions and decrease of hole concentration, CuSe, a highly Cu-vacancy doped compound exhibits monovalent state is only observed. In CuSe, higher electron density of states and shift of the gap-like structure toward higher energy in comparison with those in Cu2Se are also observed, which indicates the degeneration is enhanced in CuSe. These results reveal that Cu-Se compounds, if they precipitate in CIGS, should be recombination-path. Considering the precipitation is expected not only on surface but also at grain boundaries of CIGS, phase control during film growth should be important especially in wide gap CIGS.
(2) Characterization of Zn(S, O, OH) Buffer and Zn(S, O, OH)/CIGS Interface Fabricated by Flexible Module Process
Structural analyses reveal that the CBD-Zn(S, O, OH) buffer grown by the module-process consists of micro-crystallites. The buffer show lower long range order and higher concentration of OH-group, in comparison with CdS-layer epitaxially grown on CIGS. These structural features cause an expansion of band gap energy and rise of conduction band minimum. Band gap energy-S/(S+O) characteristics of this buffer locates higher energy side in comparison with conventional CBD-Zn(S, O, OH). Moreover, conduction band minimum of the buffer varied with dehydration. For realizing adequate conduction band alignment at the buffer/CIGS interface by the module process, control of both S-O mixing ratio and OH-group is essential. These results are consistent that a conversion efficiency above 15.5 % achieved in cells using the buffer with low OH-concentration and S/(S+O) ~ 0.5 the latter is much lower than the optimum number for conventional process.

ダウンロード成果報告書データベース(ユーザ登録必須)から、ダウンロードしてください。

▲トップに戻る