Imidazole-Functionalized Fullerene as a Vertically Phase-Separated Cathode Interfacial Layer of Inverted Ternary Polymer Solar Cells

• DOI: 10.1021/acsami.6b13461
• Publication Date: 2017-01-03T20:23:34Z
• Authors: Dan Li; Qing Liu; Jieming Zhen; Zhimin Fang; Xiang Chen; Shangfeng Yang
• Keywords: HOMO/LUMO; Active layer

By using a facile one-pot nucleophilic addition reaction, we synthesized novel imidazole (IMZ)-functionalized fullerene (C60-IMZ), and applied it as third component of inverted ternary polymer solar cells (PSCs), leading to dramatic efficiency enhancement. According FT-IR, XPS spectroscopic characterizations, elemental analysis, the chemical structure C60-IMZ was determined with average IMZ number estimated be six. The lowest unoccupied molecular orbital (LUMO) level measured by cyclic voltammetry -3.63 eV, which is up-shifted relative that 6,6-phenyl C61-butyric acid methyl ester (PC61BM). Upon doping into an active layer blend poly(3-hexylthiophene) (P3HT) PC61BM, power conversion (PCE) PSCs 3.4% under optimized ratio 10 wt %, dramatically higher than control device ITO/P3HT:PC61BM/MoO3/Ag based on binary P3HT:PC61BM (1.3%). incorporation results in enhancement absorption film, increase electron mobility device, rougher film surface beneficial for interfacial contact Ag anode. Furthermore, doped may migrate ITO cathode via vertical phase separation revealed depth consequently forming (CIL), can lower work function (WF) cathode. Thus, between improved, facilitating transport from effectiveness vertically phase-separated CIL further verified another system comprised low-bandgap conjugated polymer, poly(thieno[3,4-b]-thiophene/benzodithiophene) (PTB7), blended [6,6]-phenyl C71-butyric (PC71BM). Under PCE PTB7:PC71BM-based PSC reaches 5.3%, about 2 times (2.6%).