Wednesday Colloquia

Dipolar Donor-Acceptor Dyes as Functional Organic Materials: Transistors, Solar Cells and Photodetectors

by Prof. Frank Wuerthner (Universität Würzburg, Germany)

Wednesday, January 4, 2023 from to (Asia/Kolkata)
at AG-69 and via ZOOM webinar ( Zoom link: )
Meeting ID: 979 6325 9354 Pass code: 04072020
With their polymethine-type conjugated π-electron system, dipolar merocyanine dyes, also called donor-acceptor (D-A) dyes, feature a combination of properties that is quite distinct from other classes of dyes. Thus, they exhibit large dipole moments and oscillator strengths. If functionalized with suitable heterocyclic donor and acceptor groups these dyes can reach the cyanine-limit, leading to narrow absorption bands. Making use of these properties, already since the 1990s D-A dyes were applied for a wide variety of applications in nonlinear optics. However, as a consequence of their dipolarity, these dyes are prone to aggregation which has a pronounced impact on their bulk materials properties. Whilst not favourable for most nonlinear optical applications, D-A dye aggregation proved to be useful for organic electronics, leading to successful p- and n-type semiconductor materials. In combination with their intense absorption bands, outstanding non-fullerene acceptor materials have been derived from related A-D-A dyes. More recently, the application of D-A dyes in organic photodetectors has been reported where ultranarrow absorption bands could be supramolecularly engineered by controlling the packing of the dyes in H- and J-type aggregates. In my talk I will give an overview of our contributions to this field starting with the design of cyanine-type D-A dyes for photorefractive materials[1], continuing with fundamental studies on the aggregation of these dyes[2], and concluding with their application in organic solar cells and photodetectors[3].

[1] F. Würthner, R. Wortmann, K. Meerholz, ChemPhysChem 2002, 3, 17–31. Chromophore Design for Photorefractive Organic Materials
[2] F. Würthner, Acc. Chem. Res. 2016, 49, 868–876. Dipole-Dipole Interaction Driven Self-Assembly of Merocyanine Dyes: From Dimers to Nanoscale Objects and Supramolecular Materials
[3] J. Kim, T. Schembri, D. Bialas, M. Stolte, F. Würthner, Adv. Mater. 2022, 34, 2104678. Slip-Stacked J-Aggregate Materials for Organic Solar Cells and Photodetectors