White-light clusteroluminescence of poly(β-hydroxyvinyl N-substituted carbamate)s via through-space interactions

Abstract

White-light-emitting polymers have attracted considerable attention in the fields of solid-state lighting and flexible displays. However, achieving white light emission from single-component polymers, particularly in clusteroluminescence (CL) polymers, remains a significant challenge. Herein, we synthesize three non-conjugated luminescent poly(β-hydroxyvinyl N-substituted carbamate)s (PHNCs): PHNCs-C with steric cyclohexyl groups, PHNCs-E with side hydroxyethyl groups, and PHNCs-H with flexible n-hexyl carbon chains. All PHNCs show excitation-independent emission, which transitions to excitation-dependent emission as the excitation wavelengths increase. It is proposed that these emissions originate from the π*→n transition of carbamate in hydroxyurethane and CL of hydroxyurethane, respectively. PHNCs-C exhibits the strongest CL and possesses the highest quantum yield (17.9 %) in solution, a performance that surpasses both PHNCs-E and PHNCs-H. This finding implies that a rigid structure can enhance and stabilize the through-space interactions (TSIs) of hydroxyurethane groups, resulting in a wide cluster-size distribution and white-light emission. Theoretical calculations corroborate these experimental results, further revealing that TSIs occur between the oxygen atoms of hydroxyurethane groups, namely, through-space n-n interactions of oxygen atoms. This work not only provides valuable insights into the nature of CL and TSIs, but also offers a novel approach to preparing single-component white-light-emitting CL polymers.