Intrareticular charge transfer regulated electrochemiluminescence of donor-acceptor covalent organic frameworks

The control of charge transfer between radical anions and cations is a promising way for decoding the emission mechanism in electrochemiluminescence (ECL) systems. Herein, a type of donor-acceptor (D-A) covalent organic framework (COF) with triphenylamine and triazine units is designed as a highly efficient ECL emitter with tunable intrareticular charge transfer (IRCT). The D-A COF demonstrates 123 folds enhancement in ECL intensity compared with its benzene-based COF with small D-A contrast. Further, the COF's crystallinity- and protonation-modulated ECL behaviors confirm ECL dependence on intrareticular charge transfer between donor and acceptor units, which is rationalized by density functional theory. Significantly, dual-peaked ECL patterns of COFs are achieved through an IRCT mediated competitive oxidation mechanism: the coreactant-mediated oxidation at lower potential and the direct oxidation at higher potential. This work provides a new fundamental and approach to improve the ECL efficiency for designing next-generation ECL devices. Controlling the charge transfer between radical anions and cations is a promising way to tune the emission mechanism in electrochemiluminescence (ECL) systems. Here, the authors report a donor-acceptor based covalent organic framework, using triphenylamine and triazine building units, and demonstrate efficient ECL based on an adjustable intrareticular charge transfer.

Automated summary

This study demonstrates the efficient ECL emitter using a D-A COF with adjustable intrareticular charge transfer, leading to a significant enhancement in ECL intensity. The dual-peaked ECL patterns of COFs are achieved through an IRCT mediated competitive oxidation mechanism, providing new insights for designing next-generation ECL devices.