Designing triazatruxene-based donor materials with promising photovoltaic parameters for organic solar cells

To address the increasing demand of efficient photovoltaic compounds for modern hi-tech applications, efforts have been made herein to design and explore triazatruxene-based novel donor materials with greater efficiencies. Five new molecules, namely M1-M5 , were designed by structural modification of acceptor moiety (rhodanine-3-acetic acid) of well known experimentally synthesized JY05 dye (reference R ), and their optoelectronic properties are evaluated to be used as donor molecules in organic solar cells. In these molecules M1-M5 , triazatruxene acts as a donor unit and benzene spaced different end-capped moieties including 2-(4-(dicyanomethylene)-2-thioxothiazolidin-3-yl)acetic acid (A1), ( E )-2-(4-(1-cyano-2-methoxy-2-oxoethylidene)-2-thioxothiazolidin-3-yl)acetic acid (A2), ( Z )-2-(3′-ethyl-4′-oxo-2,2′-dithioxo-3′,4′-dihydro-2′ H ,5 H -[4,5′-bithiazolylidene]-3(2 H )-yl)acetic acid (A3), ( Z )-2-(4′-(dicyano-methylene)-3′-ethyl-2,2′-dithioxo-3′,4′-dihydro-2′ H ,5 H -[4,5′-bithiazol-ylidene]-3(2 H )-yl)acetic acid (A4) and 2-((4 Z ,4′ E )-4′-(1-cyano-2-methoxy-2-oxoethylidene)-3′-ethyl-2,2′-dithioxo-3′,4′-dihydro-2′ H ,5 H -[4,5′-bithiazolylidene]-3(2 H )-yl)acetic acid (A5) respectively, as acceptor units. The electronic, photophysical and photovoltaic properties of the designed molecules M1-M5 have been compared with reference molecule R . All designed molecules exhibit reduced energy gap in the region of 1.464-2.008 eV as compared to reference molecule (2.509 eV). Frontier molecular orbital (FMO) surfaces confirm the transfer of charge from donor to acceptor units. All designed molecules M1-M5 exhibited an absorption spectrum in the visible region and they were broader as compared to that of reference R . Especially, M5 with highest λ max value 649.26 nm and lowest transition energy value 1.90 eV was accredited to the strong electron withdrawing end-capped acceptor moiety A5. The highest value of open circuit voltage ( V oc ) 1.02 eV with respect to HOMO donor -LUMO BTP-4Cl was shown by M5 among all investigated molecules which was 0.15 V larger than reference molecule R . The designed molecule M5 is proven to be the best candidate for both electron and hole transport mobilities due to its smallest λ e (0.0212 eV) and λ h (0.0062 eV) values among all studied molecules. Five new molecules ( M1-M5 ) were designed by structural modification of acceptor moiety (rhodanine-3-acetic acid) of well-known synthesized dye JY05, and their optoelectronic prop