Confining monochromophore in dynamic polymer network for multi-stimuli responsive fluorescence-phosphorescence dual-emission

Organic fluorescence-phosphorescence dual-emission materials are attracting broad attention for their wide potential applications in information technology, display media, etc. Most reported organic systems rely on the combination of two or more luminogens that emit different-colored phosphorescence and fluorescence respectively. By contrast, the fluorescence-phosphorescence dual-emission from one single luminogen system are especially appealing, as they can offer many advantages such as improved luminescence stability, simplified fabrication process and excellent reproducibility. Nevertheless, it remains challenging to achieve stimuli-responsive fluorescence-phosphorescence dual-emission in monochromophore-based organic material. Herein, we specially designed one new bromine-substituted naphthalimide molecule and incorporated it into a dynamic carboxyl hydrogen-bonded polyacrylic acid (PAA) network to produce the robust multi-stimuli-responsive fluorescence-phosphorescence dual-emission materials. Detailed studies demonstrated that high-density carboxyl hydrogen-bonded crosslinks play important roles in the achievement of intense phosphorescence by providing a rigid environment and efficient oxygen barrier to stabilize the triplet-excited states. On this basis, responsive fluorescence-phosphorescence dual-emission characteristic was guaranteed to realize interesting luminescence color changes, because many environmental stimuli (e.g., temperature, humidity, or alcohol) were known to dissociate the carboxyl hydrogen-bonded crosslinks. This reported strategy is expected to be universal and promising for the future development of powerful organic fluorescence-phosphorescence dual-emission materials with versatile uses.