Extended Data Fig. 2: Analysis of origin of halide alloy PL peak in (BA)2PbBr4-(BA)2(MA)2Pb3I10 vertical heterostructure after heating at 80 °C.
From: Layer-by-layer anionic diffusion in two-dimensional halide perovskite vertical heterostructures
a, Bright-field image of vertical heterostructure. b, c, PL image of vertical heterostructure at room temperature and after heating at 80 °C for 40 hrs, respectively. The circled regions denote the area used for PL emission measurement of the heterostructure, bromide perovskite and iodide perovskite. Dashed lines are added in all the bright-field and PL images for the ease of distinction of bromide (light blue) and iodide (yellow) domains. Scale bars in a–c are 10 µm. d, PL spectrum of the vertical heterostructure before and after heating at 80 °C for 40 hrs. Presence of halide alloy PL peak at ~ 511 nm (dashed blue curve) is evident in bromide perovskite layer. No new PL peak (dashed red curve) is observed in iodide perovskite layer after the heating process. e, f, Bright-field and PL image of (BA)2PbBr4, respectively. g, PL image of the (BA)2PbBr4xI4(1−x) alloy formed after placing bulk crystal of (BA)2(MA)2Pb3I10 on top of (BA)2PbBr4 nanocrystal and heating it for 4 hrs at 80 °C. The bulk crystal of (BA)2(MA)2Pb3I10 is removed after the heating process to analyze the formation of (BA)2PbBr4xI4(1-x) perovskite in the bottom layer. Scale bars in e–g are 5 µm. h, PL spectrum of (BA)2PbBr4 nanocrystal at room temperature and (BA)2PbBr4xI4(1-x) alloy formed in the bottom layer after heating (BA)2PbBr4-(BA)2(MA)2Pb3I10 vertical heterostructure at 80 °C for 4 hrs.
