同時鹵素化高分子予體及小分子受體以提升高分子太陽能電池的元件效率

Simultaneous Halogenation of Polymer Donor and Small Molecule Acceptor Enhances the Efficiency of Organic Photovoltaics

李仁豪(Ren-Hao Li)

指導教授 ： 韋光華

國立交通大學/工學院/材料科學與工程系所/碩士(2020年)

摘要

在本研究中，為了更了解氟化和氯化，我們利用三個高分子(P1，P1-2Cl 和P1-2F)當作電子予體和三個小分子(ITIC，IT-4Cl 和 IT-4F)當作電子受體應用於兩相系總體異質接面太陽能電池。我們成功地藉由氟化和氯化來降低高分子和小分子的能階。此外，我們發現氯化在降低能階和擴大吸收光範圍的能力強於氟化。從UV 圖譜可發現，P1-2Cl 的高吸收係數也促成它本身好的聚集特性，而 IT-4Cl 的高吸收係數和 40 奈米的紅位移從溶液到薄膜有機會產生更多的載子。另外，我們從螢光光譜也發現高分子 P1-2Cl 的聚集特性和小分子 IT-4F 的自組裝特性增
進了能量轉移和電荷轉移的特性。另外，從原子力顯微鏡和 X 光掠角散射分析的結果顯示氟化和氯化改變了 IT-4F 與 IT-4Cl 的結晶型態。舉例來說，小分子 IT-4F 的訊號峰值顯示出它在薄膜裡可能呈現小尺寸但是分散很多所聚集而成的訊號。然而，小分子 IT-4Cl 的訊號峰值卻顯示出它在薄膜裡可能是大尺寸塊狀的訊號。另外，就 side chain 排列方向而言，小分子 IT-4F 在qz 方向比較突出，而小分子 IT-4Cl 則是在 qxy 方向。然後，我們在優化太陽能電池元件中得到最高能量轉換效率 11.30%的是 P1-2Cl:IT-4F。可惜的是雖然 P1-2Cl:IT-4Cl 有最高的短路電流和填充因子，但較低的開路電壓導致只有第二高的能量轉換效率。最後，我們認為當在設計新材料之時，氯化的低合成成本特性可使氯化被列入考慮。

關鍵字

有機太陽能電池 ； 氟化 ； 氯化

並列摘要

In this study, to elucidate the fluorination and chlorination effects on organic materials, we used three polymers (P1, P1-2Cl, and P1-2F) as electron donors and three small molecules (ITIC, IT-4Cl, and IT-4F) as
electron acceptors for application in bulk heterojunction solar cells. We successfully downshift the energy levels of both polymers and small molecules by fluorination and chlorination, owing to their electron negativity. Besides, we found that chlorination has a stronger ability to downshift the molecular energy levels and broadening the absorption range than fluorination. We
found that the aggregation property of P1-2Cl and the packing orientation and the self-assembling properties of IT-4F improve the quenching efficiency in the binary blend from PL results. The impact of chlorination and fluorination on the crystallinity is dependent on their crystalline types from AFM and GIWAXS results. For instance, the peak of IT-4F shows it has a small size but board domains dispersed in the films. However, the peak of IT-4Cl shows it has a large size in the films. Furthermore, in terms of side chain orientations, the peak of IT-4F is obvious in qz directions but IT-4Cl in qxy directions. Then, we obtained the highest PCE of 11.30% for P1-2Cl: IT-4F organic solar cells. Much to our regret, although P1-2Cl: IT-4Cl organic solar cell has the best Jsc and FF in nine binary blends, its lower Voc leads to the second-highest PCE. Above all, we think chlorination would be a promising strategy when designing newmaterials due to its ease at chemical synthesis and the low cost of precursors.

並列關鍵字

organic solar cells ； fluorination ； chlorination

參考文獻

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