| 초록 |
We have developed a new class of heptacyclic ladder-type arenes based on dithienylcarbazole and dithienylfluorene skeleton. The 3-positons of the two outer thiophenes are covalently connected with the 3- and 6-positions of the central fluorene and carbazole core, creating dithienocyclopenta-fluorene (DTCF), dithienosilolo-carbazole (DTSC), dithienocyclopenta-carbazole (DTCC) and dithienopyrrolo-carbazole (DTPC) structures. The ladder-type monomers were further polymerized with the benzothiadiazole acceptor to furnish alternating donor-acceptor copolymers PDTCFBT, PDTCCBT, PDTCFBT-C8, PDTCCBT-C8 PDTSCBT, and PDTPCBT. The devices based on PDTSCBT and PDTCCBT exhibited high hole mobility of 0.073 and 0.110 cm2V-1s-1, respectively. These mobilities are among the best performance from the amorphous donor-acceptor copolymers. The bulk heterojunction device using Si-bridged PDTSCBT as the p-type material delivered the best efficiency PCE to 5.2% with a Voc of 0.82 V, a Jsc of 11.1 mA/cm2, a FF of 56.7%. Furthermore, a novel PCBM-based n-type material, [6,6]-phenyl-C61-butyric styryl dendron ester (PCBSD), functionalized with a dendron containing two styryl groups as thermal cross-linkers, has been rationally designed and easily synthesized. In situ cross-linking of PCBSD was carried out by heating at a low temperature of 160 °C for 30 min to generate a robust, adhesive, and solvent-resistant thin film. This crosslinked network enables a sequential active layer to be successfully deposited on top of this interlayer to overcome the problem of interfacial erosion and realize a multilayer inverted device by all-solution processing. An inverted solar cell device based on an ITO/ZnO/C-PCBSD/ P3HT:ICBA/PEDOT:PSS/Ag configuration not only achieves enhanced device characteristics, with an impressive PCE of 6.22%, but also exhibits an exceptional device lifetime without encapsulation. Finally, we use an AAO template to fabricate the ordered nanostructure of C-PCBSD layers. An inverted solar cell based on an ITO/ZnO/nanostructured C-PCBSD/P3HT:ICBA/PEDOT:PSS/Ag configuration reached a high PCE of 7.1%. We envision that incorporation of the cross-linked C60 interlayer could become a standard procedure in the fabrication of highly efficient and stable multilayer inverted solar cells. |
