posted on 2024-01-23, 13:39authored byYuyue Gao, Kaiyuan Zhang, Lu Zhang, Shumeng Wang, Hui Tong, Jun Liu, Lixiang Wang
Near-infrared (NIR) light-emitting
polymers are important
because
of their many civilian and military applications. The general strategy
to design NIR-emissive conjugated polymers is to copolymerize an electron-donating
unit and electron-accepting unit to design donor–acceptor-type
copolymers. The resulting NIR-emissive copolymers suffer from low
fluorescence efficiencies and wide fluorescence spectra. In this work,
we report a series of organoboron-conjugated homopolymers with high
quality NIR light emission. The repeating unit of these homopolymers
is a double B←N-bridged bipyridine (BNBP) unit bearing diphenylether
as a large steric hindrance. Because of the rigid backbone and small
reorganization energy of BNBP, the organoboron homopolymers emit high-quality
NIR light with the emission peak wavelength of ca. 750 nm, fluorescence
quantum efficiency of ca. 0.7, and full width at half-maximum of ca.
50 nm. The application of these homopolymers as visible to NIR light
converters in NIR organic light-emitting diodes has been demonstrated.
This work indicates a new strategy of organoboron chemistry to develop
narrow-band and bright NIR-emissive polymers for practical applications.