Electron donor–acceptor (D-A) tuning to achieve soluble covalent organic polymers for optoelectronic devices

Abstract

Covalent organic polymers (COPs) have emerged as a unique class of luminescent polymers with pre-designed quasi-ordered architectures. However, their layered stacks and limited solubility preclude further processing for large-scale applications in devices, especially optoelectronic equipment. Herein, a universal strategy to adjust the electron donor–acceptor (D-A) moieties of the building blocks in COPs is proposed, achieved by in situ charge exfoliation of COP blocks into few-layer true solutions in (Lewis) acid and base media. The electron D-A moieties of the building blocks endow the COPs with the ability to accept or donate electrons, by altering the electron cloud distribution as well as the relative energy levels of the frontier molecular orbitals. The resultant soluble COPs can easily be processed into a uniform film by solution processing via the spin-coat method. The obtained COP-N achieves efficient and stable perovskite electroluminescence as a novel hole injection material on indium tin oxide, and the operating lifetime for a perovskite quantum dot light-emitting diodes device exceeds that of a poly(ethylene dioxythiophene):polystyrene sulphonate counterpart. This straightforward electronic regulation strategy provides a new avenue for the rational synthesis of processable reticular molecular polymers for practical electronic devices.