小分子施體、電子傳輸材料及透明奈米銀線電極在有機太陽能電池上之應用

Applications of Small Molecule Donors, Electron Transporting Materials, and Transparent Silver Nanowire Electrodes in Organic Solar Cells

呂誌偉(Chih-Wei Lu)

指導教授 ： 林皓武

國立清華大學/工學院/材料科學工程學系/碩士(2013年)

摘要

本篇論文研究不同的有機小分子，在真空蒸鍍製程下太陽能電池的光電特性及元件結構優化。
首先，介紹有機太陽能電池的歷史及目前發展現況，接著講解有機太陽能電池的運作機制、有機材料準備與分析、元件量測分析、元件結構種類。
論文的第二部分，介紹一系列小分子donor材料的基本光學性質，及有機太陽能電池元件的光電特性分析，針對目前有機小分子donor的發展進行文獻回顧，接著再探討與本實驗相關的有機小分子donor。在對稱小分子中，acceptor-acceptor-donor-acceptor-acceptor (A-A-D-A-A) 分子結構型態的PyCN，與C70以體積比1.5:1的共蒸鍍比例所製程的平面混合型異質接面結構元件效率最高，達4.3% ，元件表現為開路電壓 (Voc) 0.95 V、短路電流 (Jsc) 12.50 mA/cm2 、填充因子 (F.F.) 0.37。而在非對稱的小分子中我們使用donor-acceptor-acceptor (D-A-A) 分子結構型態的新型有機材料TDP搭配C70以體積比1:2的共蒸鍍比例所製程的平面混合型異質接面結構元件能量轉換效率最高，達5.6% ，元件表現為Voc 0.94 V、Jsc 11.34 mA/cm2、F.F. 0.52。
論文第三部分，將探討以不同電子傳輸層材料對有機太陽能電池元件表現的影響，我們發現TmPyPB具有熱穩定性佳、電子遷移率快 (10-3 cm2 V-1 s-1) 等優點，且應用於有機太陽能電池上也較BCP元件有更長的壽命，使TmPyPB為一個極合適的電子傳輸材料。在元件量測方面，我們也用交流阻抗頻譜分析，得到TmPyPB的元件有最小的交流阻抗。
論文的第四部份，我們用奈米銀線取代ITO進行一系列的濕式製程有機太陽能電池製作與分析，在P3HT:PCBM的材料系統上，已經達到與ITO元件相同的表現 (能量轉換效率4%)。
論文的第五部分，我們將簡介物理氣相鍍膜法，並以DBP進行初期單層膜與元件測試。

關鍵字

有機太陽能電池 ； 光電元件 ； 有機材料

並列摘要

In this thesis, I focus on the material characterization and the device optimization of small molecule organic solar cells (SMOSCs).
In the first part, I briefly review the history and development of organic solar cells (OSCs), followed by working mechanisms, material preparation, device structures and measurement of OSCs.
In the second part of thesis, before evaluting new donor compounds for SMOSCs, I review some previous reports of SMOSCs employing symmetrical or unsymmertrical small molecular donors. Among our symmetrical donor compounds, PyCN, a donor with the acceptor-acceptor-donor-acceptor-acceptor (A-A-D-A-A) molecular structure, shows the best performance in SMOSCs by utilizing the planar mixed heterojunction (PMHJ) strcuture. The optimized blend ratio is PyCN:C70 = 1.5:1 (by volume), giving a power conversion efficiency (PCE) of up to 4.3% with an open circuit voltage (Voc) of 0.95 V, short circuit current density (Jsc) of 12.50 mA/cm2, fill factor (F.F.) of 0.37. On the other hand, TDP with donor-acceptor-acceptor (D-A-A) molecular structures shows the most promising characteristics among our unsymmetrical donor systems. The TDP:C70 (1:2) PMHJ device exhibits the best performance of a PCE up to 5.6% with a Voc of 0.94 V, Jsc of 11.34 mA/cm2, F.F. of 0.52.
In the third part, the electron transporting materials, TmPyPB, B3PyPB, BCP, BP4mPy, HATCN, DPPS, ET-7 and TC-1108 had been examined for the role of electron transporting layer (ETL) in OSCs. Among them, TmPyPB possesses the advantages of good thermal stability and high electron mobility, which make it a good ETL candidate for OSCs. In the long-term light soaking test, the TmPyPB-based cells also showed longer lifetime and less deterioration than the tranditional BCP-based cells. At the last part of this section, by using AC impedance analysis, I show that the TmPyPB-based cells exhibit the lowest AC resistance among all devices.
In the fourth part, silver nanowire (AgNW) was used to replace indium tin oxide (ITO) as a transparent electrode for the OSCs. The P3HT:PCBM OSCs employing AgNW show a PCE up to 4%, which is highly comparable to the ITO-based reference cells.
In the last part, I developed a physical vapor deposition technique for solar active layer deposition. In the priliminary test, DBP thin films and the bilayer heterojunction solar cells were fabricated using this deposition method.

並列關鍵字

organic solar cell ； photovoltaic device ； organic material

參考文獻

[126] C.-C. Hsiao, A.-E. Hsiao, S.-A. Chen, Adv. Mater. 2008, 20, 1982.

[58] Z. Wang, D. Yokoyama, X.-F. Wang, Z. Hong, Y. Yang, J. Kido, Energy Environ. Sci. 2013, 6, 249.

[76] K. K. H. Chan, S. W. Tsang, H. K. H. Lee, F. So, S. K. So, Org. Electron. 2012, 13, 850.

[33] Y. S. Hsiao, W. T. Whang, S. C. Suen, J. Y. Shiu, C. P. Chen, Nanotechnology. 2008, 19, 415603.

[70] J. Zhou, X. Wan, Y. Liu, G. Long, F. Wang, Z. Li, Y. Zuo, C. Li, Y. Chen, Chem. Mater. 2011, 23, 4666.