Synthesis and Characterization of Bridged Bithiophene-Based Conjugated Polymers for Photovoltaic Applications: Acceptor Strength and Ternary Blends was written by Chen, Chiu-Hsiang;Hsieh, Chao-Hsiang;Dubosc, Martin;Cheng, Yen-Ju;Hsu, Chain-Shu. And the article was included in Macromolecules (Washington, DC, United States) in 2010.Safety of Bis(2-iodothiophen-3-yl)methanone This article mentions the following:
Six of three-component donor-acceptor random copolymers P1-P6, symbolized as (thiophene donor)m-(thiophene acceptor)n, were rationally designed and successfully synthesized by the palladium-catalyzed Stille coupling. The 4H-cyclopenta[2,1-b:3,4-b’]dithiophene (CPDT) unit serves as the donor for P1-P4, while the benzothiadiazole (BT), quinoxaline (QU), dithienoquinoxaline, and thienopyrazine (TP) units are used as the acceptor for P1, P2, P3, and P4, resp. P5 and P6 are structurally analogous to P1 and P2 except for using the dithieno[3,2-b:2′,3′-d]silole (DTS) unit as the donor. Because the band gap lowering ability of the acceptor units in the polymer is in the order TP > BT > QU presumably due to the quinoid form population in the polymers, the optical band gaps can be well adjusted to be 1.2, 1.6, and 1.8 eV for P4, P1, and P2, resp. It is found that the two bridged bithiophene units, CPDT and DTS, have similar steric and electronic effects on the P1 and P5 as well as P2 and P6, resp., leading to comparable intrinsic properties and device performances. Bulk heterojunction photovoltaic cells based on ITO/PEDOT:PSS/polymer:PC71BM/Ca/Al configuration were fabricated and characterized. Although P4 exhibits the lowest optical band gap, broadest absorption spectrum, and highest mobility, the too low-lying LUMO level hinders the efficient exciton dissociation, resulting in a low PCE of 0.7%. Compared with poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b’]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT), random copolymer P1 shows more blue-shifted, broader absorption spectrum, comparable mobility, and a higher PCE of 2.0%. In view of the fact that P1 shows a higher band gap with strong absorption in visible region, while PCPDTBT has a lower band gap to mainly absorb NIR light, a BHJ device with the active layer containing ternary blend of PCPDTBT/P1/PC71BM was investigated and achieved an enhanced PCE of 2.5%, which outperforms the devices based on the binary blending systems of PCPDTBT/PC71BM (PCE = 1.4%) or P1/PC71BM (PCE = 2.0%) under the identical conditions. Such an improvement is ascribed to the complementary absorption and compatible structure of P1 and PCPDTBT polymers. In the experiment, the researchers used many compounds, for example, Bis(2-iodothiophen-3-yl)methanone (cas: 474416-61-0Safety of Bis(2-iodothiophen-3-yl)methanone).
Bis(2-iodothiophen-3-yl)methanone (cas: 474416-61-0) belongs to iodide derivatives. Iodide-containing intermediates are common in organic synthesis, because of the easy formation and cleavage of the C–I bond. The C–I bond is the weakest of the carbon–halogen bonds. These bond strengths correlate with the electronegativity of the halogen, decreasing in the order F > Cl > Br > I. This periodic order also follows the atomic radius of halogens and the length of the carbon-halogen bond.Safety of Bis(2-iodothiophen-3-yl)methanone
Referemce:
Iodide – Wikipedia,
Iodide – an overview | ScienceDirect Topics – ScienceDirect.com