Room temperature electron-hole liquid phase in monolayer MoSi$_2$Z$_4$ (Z = pinctogen)

Abstract: Photo-excited electrons and holes in insulators, above a critical density and below a critical temperature, can condense to form an electron-hole liquid (EHL) phase. However, observing the EHL phase at room temperature is extremely challenging. Here, we introduce the monolayer MoSi$_2$Z$_4$ (Z= N, As, P) series of compounds as a promising platform for observing the EHL phase at room temperature. The higher impact of the Coulomb interactions in two dimensions helps these monolayers support the EHL phase with an increased EHL binding energy and transition temperature, along with strongly bound excitons. Our findings motivate further exploration of the MoSi$_2$Z$_4$ monolayers for realizing the EHL phase at high temperatures to harness collective phenomena for optoelectronic applications.