成果報告書詳細
管理番号20130000000769
タイトル*平成24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) ポストシリコン超高効率太陽電池の研究開発(自己組織化量子ドット)
公開日2014/5/9
報告書年度2012 - 2012
委託先名国立大学法人電気通信大学
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R & D on Innovative Solar Cells (International Research Center for Innovative Solar Cell Program) "Research and Development of Post-silicon solar cells for ultra-high efficiencies (self-organization quantum dots)" (FY2008-FY2014) FY2012 Annual Report
 
(1)In this project, fabrication of in-plane ultrahigh density QDs is one of important missions to realize the IB-SCs using the QDs. In this year, we successfully fabricated ultrahigh density InAs QDs with 0.7-1.0 ×1012 cm-2 on the GaAsSb/GaAs buffer layers and on the InAsSb wetting layers by molecular beam epitaxy (MBE). The coalescence and ripening processes of the QDs were effectively suppressed, as the results, in-plane ultrahigh density InAs QDs were obtained on the GaAs(001) substrates.

(2) Long carrier lifetime is needed for development of solar cells with high conversion efficiency. We measured long photoluminescence (PL) decay time of 4-6 ns for in-plane ultrahigh density InAs QD layers with mini-bands. It is attributed to lateral coupling of electronic wavefunction between the QDs.

(3)In-plane ultrahigh density InAs QD layer was introduced into i-GaAs layer of pin-GaAs solar cells. As a distance between the p-GaAs and the QD layer decreased, the cell performance improved. In addition, carrier lifetime of those cells was analyzed by time-resolved PL measurements. PL decay time of those samples could be modulated by changing bias voltage.

(4)Based on detailed balance model, we theoretically calculated power conversion efficiency (PCE) of intermediate-band solar cells (IB-SCs) including InAs/GaAsSb QDs. For low QD density region, the PCE decreased with increasing the QD density. As the QD density increased, the PCE rapidly increased and then saturated. When the sun concentration increased, the PCE was enhanced. These calculated results gave valuable information about design of the IB-SCs with high PCE.
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