可熱交聯富勒烯衍生物和陽極緩衝層用於溶液式製程高分子太陽能電池和鈣鈦礦太陽能電池

Abstract

本研究致力於研究可熱交聯富勒烯衍生物和陽極緩衝層用於高分子太陽能電池與鈣鈦礦太陽能電池之介面工程、形貌控制或穩定性的研究。 本研究第一部分以濕式氧化石墨烯與過渡金屬氧化物複合層當陽極緩衝層用以提升 Poly(3-hexylthiophene) (P3HT) : [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) 所形成的混摻體異質結構高分子太陽能電池，本緩衝層具備幫助電洞收集、介面修飾和較佳的大氣穩定性，這些目標的達成，有利於製備全濕式製程反式結構有機高分子太陽能電池，同時，以石墨烯複合氧化釩和石墨烯複合氧化鉬所形成之陽極緩衝層，其元件光電轉換效率可以達到 4.1 % 和 3.4 %，更進一步地，使用低能隙材料 poly{(5,6-difluorobenzo-2,1,3-thiadiazole-4,7-diyl)-alt-(3’,4”-di-(2-octyldodecyl)-2,2’;5’,2”;5’’,2’’’-quaterthiophene-5,5’’’-diyl)} (PTh4FBT) 搭配石墨烯複合氧化釩所形成的陽極氧化層其效率可以達到 6.7 %，與蒸鍍製成三氧化鉬有著相同的效率。最後，我們也使用 X 光光電子縱向分布鑑定與螢光放光圖譜來分析，我們發現氧化石墨烯能夠阻擋氧化釩先驅物的下陷，改善主動層缺陷，而能夠提升元件效率。 本研究之第二部份以紫質嵌入高分子作為一個互補吸收的策略，而適當的紫質比例可以產生全可見光譜吸收的分子，其元件短路電流可以大幅提升從 13.5 mA/cm2到 14.9 mA/cm2 ，所以元件光電效率可以從 6.8 % 到8 %，為目前紫質嵌入系統高分子光電轉換效率報導的最高效率值。更進一步的使用 1-Chloronaphthalene (1-CN) 為溶劑添加劑，幫助改善主動層溶液之溶解度和 cross-linked [6,6]-phenyl-C61-butyric styryl dendron ester (C-PCBSD) 為介面修飾層改善元件漏電流的情形，其元件短路電流可提升至 16.1 mA/cm2，效率值可以提升至 8.6 %。這紫質嵌入高分子共聚的策略規避了一般開路電壓和短路電流權衡現象，我們希望能夠作為未來設計 D-A (Donor-Acceptor) 光電高分子的策略之一。 本研究之第三部分以C-PCBSD 混摻 Fulleropyrrolidinium ions (FPI) 其比例達1:1時，經由可見光吸收光譜鑑定，仍然保有抗溶劑等性質。由於 C-PCBSD 在元件上其電子遷移率較低，我們提出以FPI 混摻在 C-PCBSD 薄膜中產生陰離子誘導電荷轉移來解決此問題，而FPI混摻後的 C-PCBSD 薄膜在空間電荷限制電流的元件上，可證實能提高電子遷移率，其μe 由 1.3 × 10-5 cm2V-1s-1 提升 6.0 × 10-5 cm2V-1s-1 ，另外我們將其應用在有機高分子太陽能電池元件上面，作為氧化鋅的修飾層，使用Poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b’]dithiophene-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene-)-2-6-diyl)] (PBDTTT-C-T) : [6,6]-Phenyl-C71-butyric acid methyl ester (PC71BM) 作為主動層材料，其元件短路電流可以從 13.1 mA/cm2提升到 15.4 mA/cm2 ，所以元件光電效率可以從 5.8 % 到6.7 %，更進一步地，將此陰極緩衝層用在鈣鈦礦太陽能電池上，其元件短路電流可以大幅提升從 14.1 mA/cm2到 19.1 mA/cm2，所以元件光電效率可以從 7.0 % 到11.9 %，除此之外此陰極緩衝層也改善了鈣鈦礦太陽能電池的熱穩定性。 本研究之第四部份以C-PCBSD 混摻於 CH3NH3PbIxCl3-x主動層中形成混摻體異質結構用於改善鈣鈦礦太陽能電池之元件表現再現性差、大氣下不穩定與薄膜針孔孔洞等問題。C-PCBSD 可改善鈣鈦礦主動層表面覆蓋率與緻密度，其可抵抗濕氣侵入，阻止溶劑侵蝕，可抑制漏電流的產生。其元件短路電流可以大幅提升從 18.7 mA/cm2到 22.3 mA/cm2，填充因子也從 70 %上升至 77 %，所以元件光電效率可以從 12.1 % 到17.2 %。最後，我們也使用可見光光譜圖和2D grazing incidence x-ray diffraction (2D-GIXRD)光繞射圖譜來鑑定與分析其薄膜在大氣下穩定性。其結果顯示，C-PCBSD混摻 CH3NH3PbIxCl3-x 薄膜元件放在大氣下180小時之後，其元件能維持在相比原本起始效率的87 %對比無混摻C-PCBSD 的CH3NH3PbIxCl3-x 薄膜元件其相比原本起始效率的50% ，這顯示其元件有良好的大氣穩定性。

The research is aimed to study the crosslinkable fullerene derivative and anodic buffer layer used in interfacial engineering, morphology control and stability of polymer solar cells and perovskite solar cell. In the first part of this study, high efficiency and long-term stable P3HT : PC61BM -based polymer bulk-heterojunction polymer solar cells (BHJPSC) are achieved by incorporating solution-processed composite anodic buffer layers (ABLs) into the devices to serve three functions : hole collection, interface optimization and long term stability. Through the excellent electron-blocking ability of the solution-processed graphene oxide (sGO) layer allows the sGO / vanadium oxide (VOx) and sGO / molybedenum oxide (MoOx) composite ABLs based BHJPSCs to reach power conversion efficiency (PCE) of 4.1 % and 3.4 %, respectively. Furthermore, when a low band gap (LBG) polymer PTh4FBT was used, its BHJPSCs containing sGO/VOx layer exhibits nearly identical PCE value of 6.7 % with the reference cell containing evaporated MoO3 interlayer. The results demonstrate that the potential of sGO/VOx as a highly efficient ABL in inverted PSCs。Finally, we use X-ray photoelectron spectroscopy (XPS) to characterize and analyze the penetration for VOx precursor. We found that sGO can effectively block the penetration of VOx precursor and improved the performance of devices. In the second part of this study, porphyrin-incorporated polymers were synthesized to circumvent the Voc-Jsc trade-offs in BHJPSCs. The rational design of porphyrin-moiety as light harvest unit onto backbone of copolymer enhanced the solubility and made it as a panchromatic light absorber. As a result, the short circuit current of device is enhanced from 13.1 mA/cm2 to 15.4 mA/cm2 with significantly improved power conversion efficiencies up to 8.0 %. Moreover, a best device performance with PCE value of 8.6 % was achieved when a processing additive (1-CN) and a C-PCBSD cathodic interlayer were introduced into the device fabrication. In the third part of this study, we developed a new cathodic buffer layer consisting of a C-PCBSD matrix and an ionic FPI dopant. Through the characterization of UV-vis spectrum, the C-PCBSD matrix can well protect the FPI dopant from washed. The incorporation of FPI can improve the electron mobility via an anion induced charge transfer (AIET) mechanism while maintaining the solvent-resistant property of the crosslinked layer. The zinc oxide (ZnO) combined with C-PCBSD / FPI layer can effectively and universally improve the performance of planar heterojunction polymer solar cells (PHJPSCs), BHJPSC, and organic metallohalide perovskite solar cells (OMPSCs). The enhanced PCE can be ascribed to the increasement of device’s short circuit current from 0.3 mA/cm2, 13.1 mA/cm2, and 14.1 mA/cm2 to 2.3 mA/cm2, 15.4 mA/cm2, and 19.1 mA/cm2, respectively. Moreover, the insertion of C-PCBSD / FPI layer can improve the thermal stability of the device by preventing direct contact between ZnO and CH3NH3PbI3 layer in OMPSCs. In the final part of this study, we demonstrate BHJ-OMPSCs with improved device characteristics and stability simultaneously by blending the C-PCBSD with CH3NH3PbIxCl3-x. The C-PCBSD can form solvent-resistant network both on the surface and in the bulk of the perovskites, which can resist the moisture incursion to prevent the interfaces from erosion, and to passivate the voids or pinholes generated in the bulk active layer to suppress the leakage. As a result, the device showed largely increased short circuit current from 18.7 mA/cm2 to 22.3 mA/cm2 with PCE up to 17.2 %. Moreover, CH3NH3PbIxCl3-x blending C-PCBSD thin films are characterized by UV-Vis spectrospcopy, and 2D-GIXRD to evulate the ambient stability. After keeping in ambient air for 180 hours, the device containing C-PCBSD still maintain 87 % of its original PCE value, while the device without C-PCBSD will droped to 50 %.