成果報告書詳細
管理番号20160000000547
タイトル*平成27年度中間年報 「高性能・高信頼性太陽光発電の発電コスト低減技術開発/革新的新構造太陽電池の研究開発/ペロブスカイト系革新的低製造コスト太陽電池の研究開発(塗布製造技術の開発)」
公開日2016/11/16
報告書年度2015 - 2015
委託先名パナソニック株式会社
プロジェクト番号P15003
部署名新エネルギー部
和文要約
英文要約Title: Development of high performance and reliable PV modules to reduce levelized cost of energy / Research and development of innovative new structure solar cells / Development of perovskite-type innovative solar cells with low production cost (Development of coating manufacturing technologies for perovskite solar cells). (FY2015-2017) FY2015 Annual Report

Our objectives are to establish technologies for high efficiency and high reliability perovskite solar cells achieving an efficiency of 20% and passing a dump heat test. In organic - inorganic halide perovskite, solid solution of organic cations, inorganic cations and halide anions can widely control characteristics of perovskite thin films such as bandgap. We prepared the perovskite thin films of HC(NH2)2PbI3 (FAPbI3) and CH3NH3PbBr3(MAPbBr3) solid solutions in order to improve an efficiency. The perovskite solar cells have a structure of glass/TCO/compact TiO2/mesoporous TiO2/ Perovskite/Spiro-OMeTAD/Au. The perovskite thin films were prepared using a solution with mixing HC(NH2)2I (FAI), CH3NH3Br (MABr), PbI2 and PbBr2 in DMF and DMSO. The composition ratios of FAPbI3 and MAPbBr3 solid solution were controlled by the molar ratio of FAI and MAI solutes. The FAPbI3 - MAPbBr3 solid solution perovskite solar cells showed a maximum efficiency at a MA/(MA+FA) ratio of 0.2. This may be due to a decrease of defects in the films by a little addition of MAPbBr3. The solar cell has achieved an efficiency of 18.5% (Voc=1.141V, Jsc=22.7mA/cm2, FF=0.715, area of 0.04cm2) by adjusting the composition ratio of MA/(MA+ FA). This result suggests that the solid solution of the perovskite absorber can further improve an efficiency. The solar cell with high reliability are required to have damp, heat and light resistances. We have focused on the heat resistance of an essential issue for solar cell materials. The heat test was carried out exposing the solar cells at 85oC. The deterioration of an efficiency progressed at three steps. In the first step, the efficiency rapidly decrease with time until 100h. In the second step, the efficiency was kept up to 200h. In the third step, the efficiency gradually decreased with time over 200h. The degradation of the efficiency is mainly attributed to a decrease of Jsc. We study on the reasons of the deterioration by characterization of the films and devices using XRD, absorbance, SIMS and SEM. In the first step, The SIMS depth profiles showed the diffusion of Li, Co, F and S elements as the dopant of Spiro-OMeTAD to the perovskite film after the heat test. The SEM images showed the formation of the voids and PbI2 phase after the heat test. These results indicate that a decrease of the Jsc is induced by the diffusion of the dopant of Spiro-OMeTAD and the formation of the voids in the first step. In the third step, the delta phase of perovskite is observed in the XRD patterns after the heat test. The phase changes from the alfa phase to the delta phase occurred by the long time exposure of 85oC. The delta phase perovskite has wider bandgap and lower absorption coefficient than the alfa phase perovskite. Therefore, the phase change induced a decrease of the Jsc in the third step. Further improvement of the heat resistance can be achieved by the suppression of the dopant diffusion and phase changes of the perovskite films.
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