Firstly, The solubility of the precursors of Cs2AgBiBr6, CsBr, BiBr3, AgBr, in DMSO is relatively low, and most of the concentrations in the literature are 0.5 M. However, the 0.5 M Cs2AgBiBr6 solution that I prepared was turbid, and needed to be filtered in order to obtain a clear and transparent solution.

Secondly, my spin-coating parameters were 900rpm 300a 5s+1800rpm 600a 25s, with dropwise addition of the counter-solvent IPA (in air) at the fifth second from the beginning of spin-coating and annealing at 285°C for 5min. The resulting film has many voids and was found to have possible AgBr and Cs3Bi2Br9 by XRD, could this be attributed to the presence of Cs2AgBiBr6? decomposition or due to incomplete annealing?

I sincerely hope to get your guidance.