Versatile, stable, and air-tolerant triplet–triplet annihilation upconversion block copolymer micelles

Abstract

Triplet–triplet annihilation photon upconversion (TTA-UC) systems based on organic molecules have emerged as a highly topical research area in the last decade. Despite their numerous advantages, however, the practical application of TTA-UC systems is often impeded by their limited dispersity in different solvents, low stability upon dilution, and poor air tolerance. Herein, we report the fabrication of a versatile, stable, and highly air-tolerant TTA-UC system based on block copolymer micelles. By polymerizing the 9,10-diphenylanthracene (DPA)-containing monomer for the core-forming block, and incorporating porphyrin platinum(II) (PtOEP) into the micellar core, spherical UC micelles were produced. The aggregated DPA moieties are in close contact with PtOEP in the micellar core, facilitating energy transfer and ensuring decent UC efficiency. Meanwhile, the choice of a poly(tert-butyl acrylate) coronal block endowed the micelles with high solubility and full functionality in various common organic solvents, and the low critical micellization concentration of the diblock copolymer ensured high stability of the micelles toward dilution. Moreover, this core–shell micellar morphology could remarkably shelter the chromophores from dissolved oxygen, which resulted in high air-tolerance for these micelles.