Carbazole linked phenylquinoline-based fullerene derivatives as acceptors for bulk heterojunction polymer solar cells: effect of interfacial contacts on device performance
作者:Pachagounder Sakthivel、Kakaraparthi Kranthiraja、Chinnusamy Saravanan、Kumarasamy Gunasekar、Hong Il Kim、Won Suk Shin、Ji-Eun Jeong、Han Young Woo、Sung-Ho Jin
DOI:10.1039/c4ta00013g
日期:——
To understand the effect of interfacial contact between the hole transporting layer (HTL) and fullerene derivatives in the active layer of bulk heterojunction polymer solar cells (BHJ PSCs), carbazole (Cz) linked phenylquinoline (PhQ)-based fullerene derivatives, PhQHCz-C61BM and PhQEOCz-C61BM, have been successfully synthesized. They are used as acceptors with a poly(3-hexylthiophene) (P3HT) donor in the active layer, and PEDOT:PSS and MoO3 were used as the HTL. Both the derivatives are highly soluble in common organic solvents and possess high thermal stability. BHJ PSCs are fabricated with configurations of ITO/PEDOT:PSS/P3HT:PhQHCz-C61BM/LiF/Al, ITO/PEDOT:PSS/P3HT:PhQEOCz-C61BM/LiF/Al, and ITO/MoO3/P3HT:PhQHCz-C61BM/LiF/Al, ITO/MoO3/P3HT:PhQEOCz-C61BM/LiF/Al, and the device characteristics were measured under AM1.5G (100 mW cm−2). Both derivatives exhibited much lower power conversion efficiencies (PCE) of ∼0.1% when PEDOT:PSS was employed as the HTL. In contrast, the PCE increases to ∼2.2% upon replacing PEDOT:PSS with MoO3 as the HTL. This is due to the fact that protonation of the pyridyl nitrogen of the acceptor in the active layer by the –SO3H group of PEDOT:PSS in the HTL, establishes a charge injection barrier at the interfacial contact and leads to restricted charge collection at the electrodes. This was indirectly confirmed by protonation of pyridyl nitrogen in PhQHCz-C61BM by the –SO3H group in p-toluenesulphonic acid.
为了了解体异质结聚合物太阳能电池(BHJ PSCs)活性层中空穴传输层(HTL)与富勒烯衍生物之间界面接触的影响,我们成功合成了咔唑(Cz)连接苯基喹啉(PhQ)的富勒烯衍生物 PhQHCz-C61BM 和 PhQEOCz-C61BM。它们被用作受体,活性层中有一个聚(3-己基噻吩)(P3HT)供体,PEDOT:PSS 和 MoO3 被用作 HTL。这两种衍生物在普通有机溶剂中的溶解度都很高,并且具有很高的热稳定性。利用 ITO/PEDOT:PSS/P3HT:PhQHCz-C61BM/LiF/Al、ITO/PEDOT:PSS/P3HT:PhQEOCz-C61BM/LiF/Al 和 ITO/MoO3/P3HT:PhQHCz-C61BM/LiF/Al、ITO/MoO3/P3HT:PhQEOCz-C61BM/LiF/Al 等配置制作了 BHJ PSC,并在 AM1.5G(100 mW cm-2)条件下测量了器件特性。当使用 PEDOT:PSS 作为 HTL 时,两种衍生物的功率转换效率(PCE)都低得多,仅为 0.1%。相反,用 MoO3 取代 PEDOT:PSS 作为 HTL 时,PCE 上升到 2.2%。这是由于 HTL 中 PEDOT:PSS 的 -SO3H 基团质子化了活性层中受体的吡啶氮,在界面接触处建立了电荷注入屏障,导致电极上的电荷收集受到限制。对甲苯磺酸中的 -SO3H 基团对 PhQHCz-C61BM 中吡啶基氮的质子化作用间接证实了这一点。