Effective D-A-D type chromophore of fumaronitrile-core and terminal alkylated bithiophene for solution-processed small molecule organic solar cells

Abstract

A new and novel organic Ï €-conjugated chromophore (named as RCNR) based on fumaronitrile-core acceptor and terminal alkylated bithiophene was designed, synthesized and utilized as an electron-donor material for the solution-processed fabrication of bulk-heterojunction (BHJ) small molecule organic solar cells (SMOSCs). The synthesized organic chromophore exhibited a broad absorption peak near green region and strong emission peak due to the presence of strong electron-withdrawing nature of two nitrile (-CN) groups of fumaronitrile acceptor. The highest occupied molecular orbital (HOMO) energy level of -5.82â €‰eV and the lowest unoccupied molecular orbital (LUMO) energy level of -3.54â €‰eV were estimated for RCNR due to the strong electron-accepting tendency of -CN groups. The fabricated SMOSC devices with RCNR:PC 60 BM (1:3, w/w) active layer exhibited the reasonable power conversion efficiency (PCE) of ∼2.69% with high short-circuit current density (J SC) of ∼9.68â €‰mA/cm 2 and open circuit voltage (V OC) of ∼0.79â €‰V.