Lewis-Pairing-Induced Electrochemiluminescence Enhancement from Electron Donor-Acceptor Diads Decorated with Tris(pentafluorophenyl)borane as an Electrochemical Protector

This study reports an effective peripheral decoration of organic donor-acceptor diads with B(C6F5)(3) for stabilizing electrogenerated radical ions. By employing a common p-type organic semiconductor benzothienobenzothiophene (BTBT) as the donor, tetracoordinate boron complexes showed improved solution electrochemiluminescence (ECL) intensity, reaching a 156-fold increase compared to that of the parent diad. The unprecedented Lewis-pairing-induced ECL enhancement is attributed to the multiple roles of B(C6F5)(3): 1) redistributing frontier orbitals, 2) facilitating electrochemical excitation, and 3) restricting molecular motions. Furthermore, B(C6F5)(3) converted the molecular arrangement of BTBT from conventional 2D herringbones into 1D pi-stacks. This robust, highly ordered columnar nanostructure allowed red-shifting of the crystalline film ECL with electrochemical doping through the electronic coupling pathways of BTBT. Our approach will facilitate the development of elaborate metal-free ECL systems.

Automated summary

This study presents a method for stabilizing electrogenerated radical ions by effectively decorating organic donor-acceptor diads with B(C6F5)(3). By employing the p-type organic semiconductor benzothienobenzothiophene (BTBT) as the donor, tetracoordinate boron complexes show improved solution electrochemiluminescence (ECL) intensity. The Lewis-pairing-induced ECL enhancement is attributed to the multiple roles of B(C6F5)(3) in redistributing frontier orbitals, facilitating electrochemical excitation, and restricting molecular motions.