Advanced Raman spectroscopy of Cs2AgBiBr6 double perovskites and identification of Cs3Bi2Br9 secondary phases

• DOI: 10.1016/j.scriptamat.2020.03.040
• Publication Date: 2020-04-08T15:50:58Z
• Authors: Paul Pistor; Michaela Meyns; Maxim Guc; Hai-Chen Wang; Miguel A.L. Marques; Xavier Alcobé; Andreu Cabot; Victor Izquierdo-...
• Keywords: Secondary phase detection; Cs2AgBiBr6; Double perovskite; 02 engineering and technology; 0210 nano-technology; Cs3BiBr9; Raman modes

Cs2AgBiBr6 double perovskites are intensely investigated as lead-free, stable alternatives to organic lead halide perovskites. In this contribution, we revise the vibrational modes of Cs2AgBiBr6 and show that Raman spectroscopy is well suited for the detection of common secondary phases such as Cs3Bi2Br9. The combined Raman analysis at pre-, near- and non-resonant conditions allows us to extract the four vibrational modes of Cs2AgBiBr6 to unprecedented detail, the most intense one at 177.3 cm-1. The experimental results are in good agreement with theoretical density functional theory calculations. In addition, we monitor the decomposition of Cs2AgBiBr6 into Cs3Bi2Br9 at temperatures above 255 °C.