The bromide anion (Br-) has 36 electrons, giving it the same electron configuration as the noble gas krypton ([Kr]), making this a matter of elementary definition.
The claim asks for the shorthand electron configuration of the bromide ion (Br-). A neutral bromine atom has atomic number 35 (configuration [Ar] 3d10 4s2 4p5 or shorthand [Ar] 3d10 4s2 4p5, full 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p5). Adding one electron to form Br- results in 36 electrons, matching the noble gas krypton ([Kr]). This is a fundamental, textbook chemistry fact (common knowledge) requiring no empirical citation. None of the retrieved papers discuss the electron configuration of Br- directly, as they focus on perovskites, catalysis, and organic synthesis.