Poly(cyclotriphosphazene-co-tris(4-hydroxyphenyl)ethane) Microspheres with Intrinsic Excitation Wavelength Tunable Multicolor Photoluminescence

Functional photoluminescent materials with a tunable multicolor emission without incorporation of metals is the current focus on luminescent materials due to their multifaceted applications. Herein, novel poly(cyclotriphosphazene-co-tris(4-hydroxyphenyl)ethane) microspheres are synthesized with size distribution of ≈0.8–1.6 µm by reacting hexachlorocyclotriphosphazene and tris(4-hydroxyphenyl)ethane at different molar ratios under facile conditions. The thermogravimetric analysis shows that the microspheres are highly thermally stable with 10% weight loss at around 500 °C. Fluorescence microscopy results show that the microspheres emit three blue, green, and red colors with an emission maximum at 487, 530, and 623 nm under different excitation wavelengths of 365, 420, and 546 nm, respectively. Furthermore, under UV and visible (365 and 420 nm) excitations, microspheres demonstrate extraordinary photobleaching stability and highly intense luminescence for expending time and repeating excitations. The microspheres also demonstrate semiconductor-like optical absorption at 235–285 nm with a tail extended to 700 nm. This exploration provides an insight for the preparation of intrinsic superior wavelength tunable multicolor emission materials from phosphazene. These microspheres are potential candidates for anti-counterfeits, solar cells, full spectrum fluorescence emitters, organic light emitting diodes, biological, catalysis applications and unlock new areas of research on multicolor photoluminescence.