Monodisperse macromolecules based on benzodithiophene and diketopyrrolopyrrole with strong NIR absorption and high mobility†
Abstract
A series of monodisperse macromolecules with A2āA1āDāA1āA2 structure based on benzodithiophene (BDT) and diketopyrrolopyrrole (DPP) BDT-4DPP, BDT-DPP-Rhod and BDT-DPP-CA were designed, theoretically calculated and synthesized, and compared with their parent molecules BDT-2DPP and BDTS-2DPP with A1āDāA1 structure. These molecules possessed highly planar molecular geometries and high crystallinity. These molecules exhibited good thermal stability with decomposition temperatures of 322ā388 °C, strong visible and near-infrared absorption (500ā1000 nm), and HOMO energy levels of ā5.38 to ā5.19 eV and LUMO energy levels of ā3.69 to ā3.46 eV. Relative to the parent molecules A1āDāA1, A2āA1āDāA1āA2 molecules exhibited red-shifted and stronger absorption. The charge transport properties of these molecules were investigated by organic field-effect transistors, and their hole mobilities were 0.036ā1.12 cmā2 Vā1 sā1. Replacing alkyl with alkylthio on BDT led to mobility enhancement by one order of magnitude.
- This article is part of the themed collection: Small Molecules and Monodisperse Oligomers for Organic Electronics