“…[174] Figure 6a illustrates the crystalline structure of Rb2CuBr3, in which a Cu atom is surrounded by four Br atoms, constituting a distorted tetrahedron [CuBr4] 3-. Similar to previous low-dimensional metal halide perovskite-like materials with STEs, [175][176] a large Stokes shift is presented in Figure 6b. The negligible photoluminescence and photoluminescence excitation (PLE) overlapping indicates a weak self-absorption effect, which is a priorcondition for achieving high LY.…”