Evoking ultra-long molecular room temperature phosphorescence of pure carbazole derivatives

Abstract

Carbazole derivatives have abundant family members and structure flexibility but are not exploited as molecular dopants for efficient doped room temperature phosphorescence (RTP) polymers. Here we demonstrate that doping a small amount of simple heavy-atom-free pure carbazole derivative into polymers via reasonable doping procedure can evoke ultralong molecular RTP without the need for isomer doping. The conventional solution-processed doped polymer films show inferior RTP, but mechanically thermoplasticizing such films can evoke ultra-long RTP, which is ascribed to that dense stacking enhances polymer rigidity and cohesion to effectively inhibit dopant molecular thermal deactivation that can not be restricted effectively by crystallization itself. Impressively, both rigid PMMA and elastic SIS can be used as doping matrix, and the doped films show ultralong RTP and photo-patterning memory effect. We believe that the combination of different N-arylcarbazole derivatives and polymers will produce unique RTP properties. This work has updated some existing RTP views and will set off a new upsurge of research on carbazole derivatives.