A nonconjugated radical polymer with stable red luminescence in the solid state
Zhaoyu Wang, Xinhui Zou, Yi Xie, Haoke Zhang, Lianrui Hu, Christopher C. S. Chan, Ruoyao Zhang, Jing Guo, Ryan T. K. Kwok, Jacky W. Y. Lam, Ian D. Williams, Zebing Zeng, Kam Sing Wong, C. David Sherrill, Ruquan Ye, Ben Zhong Tang
Abstract
Organic radicals are unstable and stable radicals usually display non-luminescent properties. Luminescent radicals possess the all-in-one properties of optoelectronics, electronics, and magnetics. To date, the reported structures of luminescent radicals are limited to triphenylmethyl radical derivatives and their analogues, which are stabilized with extended π-conjugation. Here, we demonstrate the first example of a nonconjugated luminescent radical. In spite of the lack of delocalized π-stabilization, the radical polymer readily emits red luminescence in the solid state. A traditional luminescent quencher, 2,2,6,6-tetramethylpiperidin-1-yl turned into a red chromophore when grafted onto a polymer backbone. Experimental data confirm that the emission is associated with the nitroxide radicals and is also affected by the packing of the polymer. This work discloses a novel class of luminescent radicals and a distinctive pathway for luminescence from open-shell materials.