Designing of PC<sub>31</sub>BM‐based acceptors for dye‐sensitized solar cell
Debolina Paul, Utpal Sarkar
Abstract
Abstract Three push‐pull dyes with triphenylamine as donor, thiophene as spacer and fullerene‐based acceptors have been designed using density functional theory (DFT) for dye‐sensitized solar cells (DSSCs). Here, we have done a systematic case study by varying the acceptor of dye. PCBM type of acceptors are chosen. However, the main focus lies on the fact that fullerene C 60 , which is used as conventional fullerene in PCBM, is replaced by C 30 . Further, two more structures are derived, where C 30 is changed by two of its doped counterparts, C 10 B 10 N 10 and C 10 B 10 P 10 . Structural integrity of these dyes is checked and found to be stable. Their electronic properties also provide a good insight into their characteristics. Highest occupied molecular orbital (HOMO) energy level of the dyes is positioned under the redox potential of redox couple, , which means that the dyes can be regenerated. LUMO energy value of dyes with C 30 and C 10 B 10 N 10 lies above the conduction band of semiconductor, TiO 2 , and hence electrons from the excited state of the dyes can be injected into the conduction band edge of TiO 2 . For C 10 B 10 P 10 , lowest unoccupied molecular orbital (LUMO) lies slightly below the conduction band of TiO 2 (for B3LYP functional). Therefore, few more configurations of C 10 B 10 P 10 have been checked by replacing B and P atoms with C atoms. Notably, incorporation of solvent rules out this exception and all the dyes become eligible for electron regeneration also. Time‐dependent DFT (TDDFT) studies throw light on their photochemical properties, which is one of the interim criteria for any system getting selected as a dye in the DSSCs.