Designing four naphthalene di-imide based small organic solar cells with 5,6-difluoro-3-oxo-2,3-dihydro-indene non-fullerene acceptors

Four new molecules namely bis (5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene) di-malononitrile (NDM-1), 3-fluorothiophen-2-yl) methylene)-5, 6-difluoro-3-oxo-2, 3-dihydro-1H-inden-1-ylidene) acetate (NDM-2), 5, 6-difluoro-3-oxo-2, 3-dihydro-1H-inden-1-ylidene)-3-methyl-2-thioxothiazolidin-4-ylidene) malononitrile (NDM-3) and bis (1-methyl-2, 6-dioxo-1, 2, 5, 6-tetrahydropyridine-3-carbonitrile) (NDM-4) contains central Naphthalene Di-Imide unit with different end cap acceptors have been designed for enhance the photovoltaic efficiencies. Absorption values of designed molecules lies between 400 and 490 nm, re-organization energy values varies from 0.41 to 0.67 eV for electron and 0.49 eV to 1.25 eV for hole transfer, open circuit voltages range from 4.39 to 4.73 V which indicates their better photovoltaic properties as compared to the R (3-methyl-4-oxo-2-thioxothiazolidin-5-ylidene) methyl). Designed molecules proposed large number of electronic excitations and less charge loss at donor/acceptor interfaces due to small binding energy than reference molecule. Graphic abstract: Charge transfer mechanism for adiabatic and vertical exchange. [Figure not available: see fulltext.]