Near‐Infrared‐to‐Visible Photon Upconversion by Introducing an S−T Absorption Sensitizer into a Metal‐Organic Framework

Triplet‐triplet annihilation‐based photon upconversion (TTA‐UC) of near‐infrared (NIR) light to visible light in the solid‐state remains as a great challenge due to the sensitizer aggregation that impedes the efficient triplet energy transfer. Herein, we successfully introduce a molecular sensitizer exhibiting direct singlet‐to‐triplet (S–T) absorption into a new emitter‐based metal‐organic framework (MOF) to achieve an efficient triplet sensitization and a NIR‐to‐visible TTA‐UC in the solid‐state.