Triplet-triplet annihilation photon upconversion materials coated with TiO<sub>2</sub> nanocapsules

Abstract

Triplet-triplet annihilation (TTA) upconversion is a technology that can convert low-energy light waves to high-energy light waves. The system is mainly composed of triplet sensitizers and energy receptors. The conversion mainly takes place in solution and is difficult to use as a whole molecule, which will greatly limit its application field. In this paper, by using the micelle soft template method to encapsulate the sensitizer and annihilant into the titanium dioxide shell, a highly efficient upconversion nanocapsule (TTA-UCNP) based on triplet-triplet annihilation upconversion was successfully prepared. In this study, BDP-I2 was used as the triplet sensitizer, perylene as the energy receptor, and soybean oil as the solvent. These newly synthesized nanocapsules can not only keep the up-conversion system in a solution environment, but also effectively block the quenching of triplet states by oxygen, and successfully achieve efficient upconversion luminescence in the aqueous phase. In the preparation process of the upconversion nanocapsules, we studied the effects of the type of surfactant, the amount of acid and the amount of butyl titanate on the upconversion luminescence intensity of the nanocapsules. The structure of nanocapsules was characterized by transmission electron microscope (TEM), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS), and a highly efficient TTA upconversion luminescent material coated with titanium dioxide nanocapsules was successfully prepared.