We present a large-area luminescent down-shifting layer consists of polyvinyl alcohol embedding a newly synthesized ternary Eu3+ complex. C-Si solar cell coated with this layer displayed an enhancement of ~15% in external quantum efficiency.

Mechanochemical activation is of particular significance in the field of sustainable chemistry. This technique can transform mechanical energy into a chemical reaction under solvent-free conditions, while it has rarely been used in the preparation of near-infrared (NIR) luminescent materials. Here, an NIR luminescent complex with a homogeneous shuttlelike morphology was designed and synthesized through a facile mechanochemical process at room temperature. The successful coordination of Yb 3+ with symmetrical terpyridine units and 2thenoyltrifluoroacetonate synergistically allows the obtained Yb 3+ ternary complex to reveal remarkable improvement in the NIR luminescent behavior and thermalresistant performance compared with the mononuclear complex, Yb(tta) 3 •3H 2 O. This enhancement mainly benefits from the removal of water molecules in the first coordination sphere of Yb 3+ through the introduction of terpyridines, thus preventing the diffusion of water molecules to Yb 3+ complexes, and driving the formation of the Yb 3+ complex with more effective coordination number and enhanced the NIR luminescence. This provided a promising environmentally friendly strategy to synthesize highly NIR luminescence materials for eliminating the influence of harmful organic solvents.