PffBT4T-2OD Based Solar Cells with Aryl-Substituted N-Methyl-Fulleropyrrolidine Acceptors

authors	Gaspar, H; Figueira, F; Strutynski, K; Melle-Franco, M; Ivanou, D; Tome, JPC; Pereira, CM; Pereira, L; Mendes, A; Viana, JC; Bernardo, G
nationality	International
journal	MATERIALS
author keywords	organic photovoltaics; fullerene derivatives; electron acceptors; fulleropyrrolidine acceptors; regioisomers of C-70 mono-adducts
keywords	OPEN-CIRCUIT VOLTAGE; FULLERENE DERIVATIVES; ELECTRON-ACCEPTORS; PHOTOVOLTAIC CELLS; BIS-ADDUCTS; PERFORMANCE; MORPHOLOGY; PCBM; EFFICIENT; ENERGY
abstract	Novel C-60 and C70N-methyl-fulleropyrrolidine derivatives, containing both electron withdrawing and electron donating substituent groups, were synthesized by the well-known Prato reaction. The corresponding highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) energy levels were determined by cyclic voltammetry, from the onset oxidation and reduction potentials, respectively. Some of the novel fullerenes have higher LUMO levels than the standards PC61BM and PC71BM. When tested in PffBT4T-2OD based polymer solar cells, with the standard architecture ITO/PEDOT:PSS/Active-Layer/Ca/Al, these fullerenes do not bring about any efficiency improvements compared to the standard PC71BM system, however they show how the electronic nature of the different substituents strongly affects the efficiency of the corresponding organic photovoltaic (OPV) devices. The functionalization of C-70 yields a mixture of regioisomers and density functional theory (DFT) calculations show that these have systematically different electronic properties. This electronic inhomogeneity is likely responsible for the lower performance observed in devices containing C-70 derivatives. These results help to understand how new fullerene acceptors can affect the performance of OPV devices.
publisher	MDPI
isbn	1996-1944
year published	2019
volume	12
issue	24
digital object identifier (doi)	10.3390/ma12244100
web of science category	Materials Science, Multidisciplinary
subject category	Materials Science
unique article identifier	WOS:000507308200078