Achieving Efficient TTA-UC Both in Organogels and Solvent-Free Dry Gels by Co-assembling Annihilator with Gelators

Supramolecular organogels were highly promising matrices for triplet–triplet annihilation-based upconversion (TTA-UC), but the dispersion and diffusion of the UC components were greatly relied on the microscopically interconnected solution phase in gels. Herein, 12-hydroxystearic acid (CA) and its derivatives with different alkyl chain (CA3, CA4, CA6 and CA8) were synthesized as low-molecular-weight gelators (LMMGs), and D-1 with CA attached on DPA unit was synthesized as annihilator. It was found that by co-assembling D-1 with the LMMGs, the DPA units were uniformly dispersed in the gel network regardless of whether there was a solvent or not. By chemically tuning LMMGs to optimize the morphologies of organogels, the DPA units were orderly arranged in the gel network, and showing efficient UC emission in CA, CA3, and CA8 which showed more regular morphologies. UC quantum yield of up to 13.4% (out of 50% maximum) was achieved in CA3 organogel. Moreover, when all solvents were removed from the organogels, D-1 also showed significant UC emissions, which was more than 6-fold higher than that of DPA, indicating that co-assembling the annihilator with the matrix to achieve an order arrangement presented an efficient strategy towards efficient TTA-UC in solid state.