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成果報告書詳細
管理番号20170000000137
タイトル*平成28年度中間年報 次世代材料評価基盤技術開発 研究開発項目(2)有機薄膜太陽電池材料の評価基盤技術開発
公開日2017/6/10
報告書年度2016 - 2016
委託先名次世代化学材料評価技術研究組合
プロジェクト番号P10029
部署名材料・ナノテクノロジー部
和文要約
英文要約The major target of this project is to develop evaluation technologies for chemical materials used in the fabrication of thin film organic photovoltaic (OPV) devices. For this purpose, we define reference devices, which can be fabricated in a reproducible manner and shows stable performance, and investigate various evaluation technologies with them. In FY 2016, we conducted research in evaluation of OPV under actual use conditions, fabrication of flexible PV devices, fabrication and evaluation of several kinds of Perovskite PV devices, and evaluation of basic electronic properties related to degradation.
This fiscal year, we developed several new reference PV devices, such as a semi-transparent flexible OPV device, Sn-Perovskite PV device, Bi-based quasi-Perovskite PV devices in addition to existing reference devices.
As one of the actual use tests, the semi-transparent devices were tested for zero-energy farm application where transmitted light is used to grow lettuce while some light is used to generate electricity. We found that OPV with high transparency in visible light region and with high EQE in near-IR region is most suitable for this purpose.
Another actual application of OPV we are studying is indoor use. Our OPV functioned well even under very low illumination condition (180 lx), while a-Si PV did not work. OPV is proved to be more suitable for energy harvesting than a-Si PV.
We successfully established a stable fabrication procedure of Sn perovskite PV devices and the light stability of the encapsulated devices was studied. Though the PCE of these devices were low, they showed small degradation under 1-Sun light exposure after some initial variation for several hours. We also developed another type of non-Pb, or Bi-based quasi-Perovskite devices, such as Ag3BiI6, the maximum PCE of which reached 4.3%.
Encapsulation to protect devices from moisture and/or oxygen is most important to achieve long lifetime. We fabricated OPV devices on flexible substrates with several different gas barrier properties and investigated degradation of the devices. The device on a substrate with the lowest gas barrier property showed more leak current and degradation was observed from the edge by imaging analysis.
Roll-to-roll process is an extremely efficient fabrication process and one of the advantages of OPV. Coating method, coating atmosphere, solvent of solution, laser patterning, etc. were investigated.
We conducted an acceleration test of bulk hetero-junction devices with intense light exposure to investigate lifetime prediction. We found that we can use light intensity up to 5 sun for this test since degradation curves showed almost the same behavior when they were plotted against the product of light intensity and exposure time. Under 10 sun exposure, the degradation curve was quite different and we should exclude it.
We have been refining our ability to determine energy levels of semiconductors with electron spectroscopy and Kelvin probe, which is useful for designing material and device structure. This year, we established a method to obtain energy levels of Perovskite materials by using a log-log plot of UPS and LEIPS data. We determined energy levels of Sn Perovskite materials, which clarified how the device property is improved by addition of SnF2.
We applied thermally stimulated current (TSC) measurement to bulk heterojunction PV devices and both Sn and Pb-based Perovskite PV reference devices and found that information about traps in the bulk of active materials. It also gave information on phase transition of Perovskite materials.
We measured temperature dependence of Voc of Perovskite reference devices to investigate energy loss mechanism of the PV device. For Sn Perovskite PV, main cause of its large energy loss seems to be attributable to the interface in the device. For bulk hetero-junction devices, it is due to energy offset between donor and acceptor, which ends up in non-radiative energy loss.
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