共軛聚合物混溶性於高效三元有機太陽能電池光伏性能和堆疊型態的影響

Effects of the Miscibility of Conjugated Polymer Donors on Photovoltaic Performance and Stacking Type of Highly Efficiencnt Ternary Organic Solar Cells

彭雅絹(YA-JUAN PENG)

指導教授 ： 黃慶怡

國立臺灣大學/工學院/高分子科學與工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202104508

摘要

本研究探討在高效率PM6:Y6系統中加入不同共軛聚合物供體材料J51、FTAZ和PTO2形成供體/供體/受體系統的三元太陽能電池，我們使用紫外-可見光光譜儀(Ultraviolet–visible spectroscopy, UV-Vis)、光致發光光譜儀(Photoluminescence, PL)、原子力顯微鏡(Atomic Force Microscope, AFM)和低掠角廣角X射線散射(Grazing-Incidence Wide-Angle X-ray Scattering, GIWAXS)來分析材料之間的混溶性對三元共混薄膜的光電和型態特性的影響。其中，第三元材料J51、FTAZ和PTO2都展現出與PM6具有良好相溶性，並出現在富含PM6的區域中。值得注意的是，χJ51/Y6(1.79 K)和χJ51/PM6(0.34 K)之間較大的差異增強了Y6的分子堆積，然而，J51分子構型容易產生空間位阻而限制供體相內的電荷轉移和收集，從而導致光伏性能下降。當加入FTAZ時，則同樣觀察到Y6的分子堆疊強度增強(χY6/FTAZ=1.24 K)，並因為具有較低的χFTAZ/PM6(0.13 K)使FTAZ/PM6形成良好混和的供體相，因此有效提升供體材料的HOMO能階使三元元件之VOC增加，並促進電荷傳遞和收集從而增強FF，進而提升能量轉換效率(power conversion efficiency, PCE)從14.3%(二元)提高至15.3%(三元)。在這三種測試的第三元聚合物供體中，PTO2展現出與PM6的最高混溶性大大增強了供體相有序的堆疊型態，並具有比PM6更深的HOMO能階有效提升VOC，因此，元件的PCE從14.8%(二元)提升至15.6%(三元)。最後，我們還研究了1-chloronaphthalene(CN)作為溶劑添加劑時，對PM6:PTO2:Y6和PM6:PTO2:BTP-eC9三元混摻系統的影響，證實少量的CN可以有效優化共混形態並實現元件的長期穩定性，獲得最高PCE為17.05和18.01%的優異表現。因此，通過我們對供體/供體/受體三元系統中的混合形態和光伏性能的一系列研究，期望我們的結果可以提供未來研究學者們設計穩定的高性能三元太陽能電池提供了有效的策略。

關鍵字

三元太陽能電池 ； 共軛聚合物 ； 混溶性 ； 能量轉換效率

並列摘要

In this study, conjugated donor-type polymers of J51, FTAZ and PTO2 have been investigated as a third component in PM6:Y6-based ternary organic photovoltaic systems. We used UV–Vis spectroscopy, photoluminescence spectroscopy, atomic force microscopy, and grazing-incidence wide-angle X-ray scattering to analyze the effects of the miscibility between the components on the optoelectronic and morphological properties of the resulting ternary blend films. All of these three minor components J51, FTAZ, and PTO2 exhibited good miscibility to PM6, and were expected to stay within the PM6-rich domains. In particular, the large difference between the values of χY6/J51 (1.79 K) and χJ51/PM6 (0.34 K) enhanced the molecular packing of Y6 and affected the energy level alignment of PM6/J51. In addition, the distortion of J51 molecules associated with the steric hindrance impeded the charge transfer and collection within the donor-rich domains, leading to lower values of JSC, VOC, FF, and PCE. When adding FTAZ, the enhancement of the molecular packing of Y6 (χY6/FTAZ = 1.24 K) with a low value of χFTAZ/PM6 (0.13 K) is also observed, which helps to form a well-mixed FTAZ/PM6 blend. Thus, the effective HOMO energy level of the D moieties is increased, thereby promoting the increment of VOC of its ternary OPVs. The embedding of FTAZ also promoted charge transport and collection and enhanced the FF and PCE—with the latter increasing from 14.3% (binary) to 15.3% (ternary). Of these three tested third polymers, PTO2 displayed the highest miscibility with PM6, which greatly enhanced the molecular packing of donor-rich domainds. In addition, PTO2 has a deeper HOMO energy level than that of PM6, increasing the value of VOC. Accordingly, the PCE of the device is promoted from 14.8% (binary) to 15.6% (ternary). Finally, we examined the effects of 1-chloronaphthalene(CN) as a solvent additive on the ternary blend systems of PM6:PTO2:Y6 and PM6:PTO2:BTP-eC9. Based on the fact that the very small amount of CN can optimize the blend of morphology and achieve long-term stability of the devices, the PCEs of the PM6:PTO2:Y6 and PM6:PTO2:BTP-eC9 ternary devices were observed to reach a high value of 17.05 and 18.01%, respectively. Through a series of our studies on blend morphology and photovoltaic performance in the ternary donor/donor/acceptor systems, we believe our results provide effective strategies for the design of stable high-performance ternary OPVs.

並列關鍵字

ternary organic photovoltaics ； conjugated polymer ； miscibility

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