Cold sintering of hybrid copper-iodides in transparent ceramics using dolomitization-inspired densification

The non-toxic hybrid luminescent copper(I) iodides are competitive solution for environmentally sustainable applications in solar cells, lighting, and detectors. However, their susceptibility to elevated temperature and oxidation creates great hurdles for technological integration due to the lack of suitable encapsulation. Inspired by the mechanism and kinetics of dolomitization in geology, we propose a cold sintering process that enables the densification of highly transparent SrF₂ ceramic at 150 ^oC, which can serve as a matrix for hybrid copper iodides. The introduction of cation-rich (Sr²⁺ rich) solution accelerates the rate-determining precipitation of solvated ions, which largely promotes the cold sintering process at low temperature. During the proposed cold sintering process, the synergistic effect of uniaxial pressure and temperature generates a continuous dispersion of melted hybrid copper iodide ([Cu₄I₄(pph₂Et)₄]) throughout the thermally conductive matrix, leading to an external quantum efficiency of 50%, enhanced resistance to thermal quenching, and superior stability after 100 h of damp-heat test. By encapsulating various hybrid copper iodides, the strategy is applicable for not only full-spectrum white lighting, but also X-ray imaging.