Rational design of near-infrared dyes based on boron dipyrromethene derivatives for application in organic solar cells

Theoretical investigations about the effect of electron-withdrawing groups on proprieties of A-π-D-π-A type small molecules donor for organic solar cells

Taking the reporting donor SM0 as reference, three new A-π-D-π-A type small molecules donors (SM1, SM2, and SM3) were designed via replacing acceptor moieties. The molecular proprieties affecting the cell performance, such as, frontier molecular orbital, open circuit voltage (V_oc), absorption spectrum, vertical and adiabatic ionization potential, vertical and adiabatic electronic affinity, and energy driving force ΔE_L-L were investigated through the density functional theory (DFT) and the time dependent density functional theory (TD-DFT). All new designed molecules exhibit reduced energy gap, show a red shift absorption band, small energy binding E_b, moderate V_oc, and improve the creation of hole and electron as compared to SM0, which demonstrate that these new designed molecules could be used as a promising donors materials for organic solar cell. Additionally, the three new designed molecules present a larger amount charge transfer q_CT, a longer length charge transfer D_CT than SM0 and have a smaller reorganization energy of hole λ(h) which improve the charge carrier mobilities.

New Design Strategy Toward NIR I Xanthene-Based Dyes

An effective design strategy with an efficient synthetic route to xanthene-based far-red to near-infrared dyes is reported. The dyes were prepared by the Suzuki cross-coupling of the electron-poor fluorescein ditriflate with the electron-rich boronic acid/ester-functionalized pyrrole (2C/3C) and indole (2D/3D) moieties. Upon treatment with trifluoroacetic acid, the closed nonfluorescent forms of the dyes (2C and 2D) ring-opened to their fluorescent forms (3C and 3D). The absorption maxima were 665 and 704 nm, while the emission maxima were 717 and 719 nm for 3C and 3D, respectively. The closed forms of the dyes were soluble in chloroform and acetonitrile. To test the efficacy of the dyes as probes, a turn-off fluoride ion probe was prepared from 3C, which consisted of a silyl ester receptor. The probe responded strongly to low concentrations of fluoride, carbonate, and acetate ions, weakly to phosphate ions, but not to the other halogens. Moreover, the probe can detect the minimum concentration of F^- in water.

aza-BODIPY synthesis towards vis/NIR functional chromophores based on a Schiff base forming reaction protocol using lactams and heteroaromatic amines

The Schiff base forming reaction of lactams and heteroaromatic amines led to creation of a new class of aza-BODIPY analogues as visible and near infrared functional chromophores.