Research Progress of Porous Framework-Based Triplet-Triplet Annihilation Upconversion Materials

Triplet-triplet annihilation upconversion (TTA-UC) is an anti-Stokes process that converts low-energy photons into high-energy photons, holding significant promise for applications in solar energy harvesting, photocatalysis, and bioimaging. However, the main operating environment for efficient TTA-UC is an oxygen-free solution, which severely limits its practical applications. Recently, porous framework materials, such as metal-organic frameworks (MOFs) and porous aromatic frameworks (PAFs), have emerged as promising platforms due to their diverse functional and structural characteristics. These materials provide promising platforms for developing efficient, oxygen-resistant, solid-state TTA-UC systems. In this review, we first outline the key parameters and status of porous framework-based TTA-UC materials, providing a detailed analysis of the intrinsic relationship between structure and performance. We then summarize recent advances in this class of materials and highlight their applications in bioimaging, sensing, and photocatalysis. Finally, we discuss the prevailing challenges and propose prospective solutions.