Fig. 1: Crystals structure, luminescence, and Li-dopant concentration characterization.

a Crystal structure of (PEA)₂PbBr₄^58,59. b Bright-field, UV and X-ray images of 1:1 Li-(PEA)₂PbBr₄ single crystal. The lengths of black and white bars are 1 cm. c Powder XRD pattern of four different Li-doped crystals. d Li to Pb XPS and ICPMS signal ratios as a function of precursor ratio.