Light-Frozen Dynamic Covalent Synthesis of Organic Semiconducting Materials

Designing the materials of tomorrow requires the development of conceptually different synthetic methodology.

Creating large conjugated molecular scaffolds often requires many synthetic steps, hindering their exploration and the discovery of new organic semiconductors.

PhotoFreeze is a synthetic methodology that combines the best features of dynamic covalent chemistry and conventional covalent synthesis.

With this novel chemical approach, a wide range of new functional materials will be developed, namely underrepresented electron-poor organic semiconductors, studied for their important optoelectronic properties.

These materials have become essential to the development of organic electronic devices such as Organic Light Emitting Diodes (OLEDs), Organic Solar Cells (OSCs) or Organic Field Effect Transistors (OFETs) among others.

The key advantage of PhotoFreeze is that a complex dynamic covalent library of nanographene-based polyimines in exchange can be quickly and irreversibly frozen by visible-light irradiation via photocyclization. Such reaction retains and even strengthens the electronic conjugation between the starting materials.

This method holds a great promise in the development of a wide variety of imide-based complex conjugated molecular architectures.

By varying the reactants stoichiometry, composition, geometry and reaction conditions, a specific target molecule can be prepared in a one pot-sequence.

PhotoFreeze will be applied to synthesize various architectures including linear, helical, cyclic graphene nanoribbons, conjugated macrocycles and covalent organic framework.

The methodology described here allows the synthesis of otherwise inaccessible or very tedious to prepare large and tuneable structures, and solves fundamental synthetic challenges.

The proposed materials hold a great promise for novel high performances organic electronics and will be integrated into relevant devices, guiding the design of future n-type organic semiconductors.