成果報告書詳細
管理番号20140000000622
タイトル平成22-25年度成果報告書 最先端研究開発支援プログラム 低炭素社会に資する有機系太陽電池の開発 高効率有機薄膜太陽電池の作製(2)
公開日2015/3/31
報告書年度2010 - 2013
委託先名JX日鉱日石エネルギー株式会社
プロジェクト番号P09026
部署名新エネルギー部
和文要約有機薄膜太陽電池の耐久性向上および集積構造サブモジュールの変換効率向上を目的として、下記検討を行った。
1)耐久性への影響因子把握およびデバイス耐久性の向上検討
 各種封止材、光電材料の組合せ検討を行った結果、封止材と光電材料を適切に選定すれば85℃での耐熱試験1000h後の性能低下が10%以下の素子を作製できた。また、耐光試験(1SUN連続照射)の劣化素子の膜組成をSIMS分析した結果、光電層内部への電極材料に含まれるLiの拡散が確認された。そこでP3HT系ガラス基板素子で電極層の改良を行った結果、耐光試験で1万時間を超えても、初期60hで7%程度性能低下した後は、7%程度の性能低下しか起こらないことが確認できた。さらに集積構造モジュールでも10%性能低下時間を耐湿試験(85℃85%RH)で2000h以上、耐光試験で約1万h程度を達成できた。また、屋外暴露試験と加速耐久試験の劣化挙動解析を行った結果、積算照射光量で整理できることが分かり、P3HT系ガラス基板素子では10年相当の耐久性が見込まれることが示唆された。また、サブテーマ(2)の他機関が開発した高効率材料を入手し、高耐久素子作製手法と組合せて、耐久性検証を行った結果、開発した電子輸送層では、初期効率8%は達成できたが、耐光試験での性能低下が大きかった。そこで電子輸送層材料の改良を行った結果、初期効率、耐光性とも良好な電子輸送層材料を見出すことができ、初期効率8%で耐光試験700h後の性能低下が約4%と高効率、高耐久の両立を実証できた。
2)集積構造サブモジュールの変換効率向上検討
 高効率な集積構造モジュール作製のため、各種パターニング手法の調査、予備検討を実施した結果、基板全面に製膜した光電層を適切な強度のUVレーザーでスクライブすることで、パターン幅100μm程度の微細パターン形成が可能なことを確認した。そこで、レーザースクライブ装置を導入し、パターニング条件検討を行った結果、メカニカルスクライブに比べ、耐熱性が悪化するが、条件改良により耐熱性を改善できること、最適条件の選定で面積効率を98.1%まで向上できることを見出し、モジュール効率として4.2%(開口部面積基準)の集積構造サブモジュールを作製できた。
英文要約In our effort to improve the durability and power conversion efficiency of organic thin-film solar cells(OPV), and sub-modules, we have been focusing on the following topics.
1) Determining the factors affecting durability and improving device durability
We studied the thermal stability of devices using different combinations of encapsulants and photoactive materials and found that by using the proper encapsulant and photoactive material, we could fabricate a highly durable device that showed less than a 10% loss in power conversion efficiency after 1000 hours of thermal testing (85-C). A SIMS measurement of a light-soaked device (1 sun, continuous illumination) showed that Li ions had migrated from the electrode to the photoactive layer. We developed a new electrode material and found that the decrease in performance of P3HT based glass substrate devices stopped after an initial decrease of around 7% (60 hours). After the initial decrease, the additional decrease in performance was only around 7% after more than 10,000 hours of light soaking. We used this electrode material to fabricate sub-modules and tested its durability, and found that the performance of the modules decreased less than 10% after both humidity testing (85°C/85%RH) for more than 2,000 hours and light soaking for about 10,000 hours. And the results of outdoor exposure tests and indoor accelerated aging tests showed that performance decreased linearly with the increase in cumulative irradiance, and suggested that the lifetime of P3HT based glass substrate devices would be more than 10 years. We obtained some high efficiency materials developed by other researchers and combined these with our durable device architecture, and conducted durability tests on the resulting devices. It was found that the light resistance of the devices made with a newly developed electron transport layer (ETL) was quite low, although we did achieve 8% initial efficiency. We therefore modified the ETL materials and found a material which showed high initial efficiency and good durability. Using this ETL material, we were able to fabricate devices which showed a high initial efficiency of 8% plus good durability, in that performance decreased by just 4% after a 700hr light soaking test.
2) Improving the power conversion efficiency of sub-modules
In an effort to fabricate highly efficient sub-modules with monolithic integration, we tested several patterning methods. We were able to pattern the photoactive layers with a pattern width of less than 100 microns by scribing with a UV laser. We found that the modules fabricated using the laser scribing method had lower thermal stability than those fabricated with a mechanical scriber, although thermal stability could be improved by optimizing the laser scribing conditions. Ultimately, we were able to fabricate modules which had a high aperture ratio (98.1%) and efficiency (4.2%, based on designated illumination area) using the laser scribing method.
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