M. Nazim

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

A new and novel organic π-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 –5.82 eV and the lowest unoccupied molecular orbital (LUMO) energy level of –3.54 eV were estimated for RCNR due to the strong electron-accepting tendency of –CN groups. The fabricated SMOSC devices with RCNR:PC60BM (1:3, w/w) active layer exhibited the reasonable power conversion efficiency (PCE) of ~2.69% with high short-circuit current density (JSC) of ~9.68 mA/cm2 and open circuit voltage (VOC) of ~0.79 V.

Furan-bridged thiazolo [5,4-d]thiazole based D–π–A–π–D type linear chromophore for solution-processed bulk-heterojunction organic solar cells

Novel furan-bridged thiazolo[5,4-d]thiazole based π-conjugated organic chromophore (RFTzR) was formulated and utilized for small molecule organic solar cells (SMOSCs). The presence of furan spacer along with two terminal alkyl units significantly improved its absorption and solubility in the common organic solvents. RFTzR exhibited the reasonable HOMO and LUMO energy levels of −5.36 eV and −3.14 eV, respectively. The fabricated SMOSCs with RFTzR (donor) and PC60BM (acceptor) as photoactive materials presented relatively high power conversion efficiency of ∼2.72% (RFTzR : PC60BM, 2 : 1, w/w) along with good open-circuit voltage of ∼0.756 V and high photocurrent density of ∼10.13 mA cm−2, which might attribute to its improved absorption, electrochemical properties and the presence of strong electron-withdrawing furan moieties.