成果報告書詳細
管理番号20140000000594
タイトル*平成25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(広バンドギャップシリコン系薄膜)
公開日2014/12/27
報告書年度2013 - 2013
委託先名シャープ株式会社
プロジェクト番号P07015
部署名新エネルギー部
和文要約
英文要約Title: NEDO Innovative PV Technology, Thin Film Full Spectrum Solar Cells with Low Concentration Ratios, Wide Band gap Si Based Thin Film.
(FY2008-FY2014) FY2013 Annual Report

In this year, we have tried improving i- and p- layers in a wide band gap cell (a-SiO(C):H cell) in order to obtain high open-circuit voltage (Voc) above 1.10 V (1.20 V in the case of low magnification condensing) and short-circuit current density (Jsc) of 9.5 mA/cm2.
At first, we focused on i-layer made of wide band-gap materials. Wider band-gap (Eopt) and higher photo-conductivity were obtained by changing the material from a-SiC to a-SiO. We applied the a-SiO to i-layer of a-Si based cells, however, the IV characteristics, especially Fill factor, were worse than those of i-a-SiC. This may be caused by the band-offset between p- and i-layers. Therefore we tried adding Boron to i-layer near p-layer to improve the electronic structure in p/i interface. The fill-factor (F.F.) successfully improved. This indicated that the IV characteristics are expected to improve by controlling the Fermi energy level of the initial i-layer.
Next, we focused on p-layer. When the material of p-layer was changed from a-SiC to a-SiO, the conductivities of p-a-SiO films were lower than those of p-a-SiC at the same Eopt. But when the a-SiO films were deposited under the conditions of much higher concentrations of B2H6 and CO2, much wider Eopt and higher conductivity (e.g. Eopt = 3.06 eV, σd = 7.9×10-6 S/cm) were obtained. We applied the a-SiO made from rich B2H6 and CO2 to p-layer of a-Si based cells, but the IV curves had problems with high series resistance. We analyzed the a-SiO films in detail. Then, it is found that these films includes BOxHy crystals and these crystals contribute higher conductivity. These crystals, however, volatilized over 100 ºC, and for this reason, when these films were annealed, conductivity exponentially decreased.
Besides, we investigated about the interface between TCO and p-layer. We obtained the a-SiC cell with Jsc = 9.3 mA/cm2, Voc = 1.00 V, F.F. = 0.65 and Eff. = 6.0% when the p-type micro-crystalline Si layer was inserted between SnO2 and p-a-SiC layer.
As a result, we succeeded obtaining the p- and i- layer having wider Eopt and higher conductivity. But these higher properties have not contributed to improve the IV characteristics. We now study about each layer including the interface between layers to develop these properties and reach Voc = 1.10 V and Jsc = 9.5 mA/cm2.
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