Halogen substitution regulates the phase transition temperature and band gap of semiconductor compounds

(CH3CH2NH3)3BiX6 and (CH2ClCH2NH3)3BiX6 (X = Cl, Br) obtained by halogen substitution, not only realize the adjustment of phase transition in a relatively wide temperature range, but also optimize the semiconductor performance. It will promote the exploration and construction of semiconductor materials with tunable temperature and lower band gap.