New narrow-band-gap conjugated copolymers based on benzodithiophene: Synthesis and photovoltaic properties

Synthesis, Characterization, and Electropolymerization of Extended Fused-Ring Thieno[3,4-b]pyrazine-Based Terthienyls

“…With the exception of the HOMO level of P[T4] , all of the HOMO and LUMO energy levels given in Table 3 follow expected trends, which results in band gaps of 0.8–0.9 eV for the polymers of the extended fused-ring TP analogues. It should be noted that the E g values of P[T3] – P[T5] given here are lower than that reported for all of the copolymeric materials given in Figure 3 [ 23 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 51 , 53 , 54 ], with only the two homopolymers of acenaphtho[1,2- b ]thieno[3,4- e ]pyrazine ( P1a , P1b ) giving lower band gaps [ 23 , 37 , 38 ]. This is consistent with previous reports of TP-based materials which have shown that TP and its extended fused-ring analogues are stronger donors than nearly all other commonly applied building blocks [ 25 , 28 , 35 ] and thus the inclusion of additional monomeric units stabilizes the polymer HOMO and leads to an increase in E g .…”

“…As noted with the electrochemical band gaps, the optical band gaps of 0.82–0.99 eV for P[T3] – P[T5] are lower than that reported for all of the copolymeric materials given in Figure 3 [ 23 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 51 , 53 , 54 ], which reinforces the assertion that the inclusion of additional monomer units can allow more soluble or processible films and can generate deeper HOMO levels, but this always comes at the cost of increased band gaps. Lastly, comparison of P[T4] with its previously reported analogue P5 ( Figure 3 ) reveals a significant difference in E g (0.89 vs. 1.21 eV [ 51 ]).…”

“…Such extended fused-ring analogues have included acenaphtho[1,2- b ]thieno[3,4- e ]pyrazines ( 3 ) [37,38,39,40,41,42,43,44,45,46,47], dibenzo[ f,h ]thieno[3,4- b ]quinox-alines ( 4 ) [45,46,47,48,49,50,51], thieno[3′,4′:5,6]pyrazino[2,3- f ][1,10]phenanthroline ( 5 ) [52,53], trithieno[3,4- b :3′,2′- f :2″,3″- h ]quinoxaline ( 6 ) [44,54], and trithieno[3,4- b :2′,3′- f :3″,2″- h ]quinoxaline ( 7 ) [44,54]. Extended fused-ring TPs are generally applied as stronger acceptors in D-A materials [47], yet these monomers are in reality ambipolar units in the same manner as traditional TPs [35].…”

“…While the majority of TP-based materials utilize various 2,3-difunctionalized TP monomers, a number of extended fused-ring analogues ( Figure 2 , 3 – 7 ) [ 36 ] have also been utilized as potentially improved building blocks in conjugated materials [ 23 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. Such extended fused-ring analogues have included acenaphtho[1,2- b ]thieno[3,4- e ]pyrazines ( 3 ) [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ], dibenzo[ f,h ]thieno[3,4- b ]quinox-alines ( 4 ) [ 45 , 46 , 47 , 48 , 49 , 50 , 51 ], thieno[3′,4′:5,6]pyrazino[2,3- f ][1,10]phenanthroline ( 5 ) [ 52 , 53 ], trithieno[3,4- b :3′,2′- f :2″,3″- h ]quinoxaline ( 6 ) [ 44 , 54 ], and trithieno[3,4- b :2′,3′- f :3″,2″- h ]quinoxaline ( 7 ) [ 44 , 54 ]. Extended fused-ring TPs are gener...…”

Achievements in polycondensation and condensation polymers

“…In addition to the mentioned traditional condensa tion polymers, there is scarce information about the synthesis and properties of other types of polymers that have rapidly developed in recent years [301][302][303][304][305][306][307][308][309][310][311][312][313][314]: poly(arylene ether sulfide sulfones), polyphenylquin olines, polyphenylquinones, polybenzotriazoleim ides, polyamidines, poly[bis(itaconimides)], and poly(arylene)thiophenones. …”