Nile red-based AIEgen for highly fluorescent polymer particles and its application in light-scattering fluorescent films.

Organic luminophores with superior solid-state luminescence are urgently required in various fields, such as lighting, display, sensing, and solar energy conversion. However, to achieve their highly efficient luminescence still remains a challenge. Herein, a newly designed Nile red derivative, Nile-DPA-VB, is successfully obtained to exhibit aggregation-induced emission characteristics with the photoluminescent quantum yield (PLQY) of 11.45%. Such PLQY could be further promoted to 53.45% when Nile-DPA-VB is polymerized undergoing precipitation polymerization process, where the confined aggregation microenvironment severely restricts the intramolecular motions of Nile-DPA-VB. Remarkably, Nile-DPA-VB is ultrasensitive to the polarity and steric effect, enabling the real-time monitoring of aggregation microenvironment evolution for precipitation polymerization. The microphase separation and dynamic hardening for the nucleation and growth processes are visually demonstrated, which contribute dominantly to the high-efficiency luminescence. Finally, by doping the as-prepared fluorescent polymeric particles into polymethyl methacrylate, functional films with high luminescence and high haze are achieved to show the potential in lighting. These findings clearly demonstrate the significant role of polymerization in constructing high-efficiency solid-state luminescent materials for practice.