Molecular-weight engineering of high-performing diketopyrrolopyrrole-based copolymer bearing high π-extended long donating units

Local structuring of diketopyrrolopyrrole (DPP)-based oligomers from molecular dynamics simulations

The microscopic structure of high mobility semiconducting polymers is known to be essential for their performance but it cannot be easily deduced from the available experimental data. A series of short oligomers of diketopyrrolopyrrole (DPP)-based materials that display high charge mobility are studied by molecular dynamics simulations to understand their local structuring at an atomic level. Different analyses are proposed to compare the ability of different oligomers to form large aggregates and their driving force. The simulations show that the tendency for this class of materials to form aggregates is driven by the interaction between DPP fragments, but this is modulated by the other conjugated fragments of the materials which affect the rigidity of the polymer and, ultimately, the size of the aggregates that are formed. The main structural features and the electronic structure of the oligomers are fairly similar above the glass transition temperature and at room temperature.

Molecular Weight Engineering in High-Performance Ambipolar Emissive Mesopolymers

Mesopolymers with high solubility, free of structural defects, and negligible batch-to-batch variation open a new avenue for organic optoelectronics. Organic light emitting transistors that combine the functions of organic light-emitting diodes and organic field-effect transistors. However, charge transport ability and light emitting strength are contradictory within one conjugated polymer. Herein, three low-molecular-weight mesopolymers with thienopyrroledione-benzothiadiazole repeating units (meso-TBTF) were obtained. The mesopolymers show strong solid-state emission and high ambipolar carrier mobility. The molecular weights of meso-TBTF can be tuned by polymerization temperature. The mesopolymers have photoluminescence quantum yields (PLQY) of about 50 % in solution and 10 % in solid state. Polymer light emitting diodes of this material are fabricated to explore its potential use in optoelectronic devices.