Efficient spin-doublet near-infrared emission beyond 800 nm via intramolecular charge transfer in a quasi-planar donor–acceptor structure

Abstract

Donor–acceptor type near-infrared luminescent radicals were synthesized in high yields via an iodinated building block. The rigid, quasi-planar configuration promotes the formation of an intramolecular charge-transfer excited state with non-bonding characteristics. This ultimately leads to efficient deep-NIR emission beyond 800 nm, realizing a photoluminescence quantum efficiency as high as 21%.