Electron-hole liquid formation in formamidinium lead bromide perovskite FAPbBr3

We observe radiative recombination from an electron-hole liquid (EHL) in a thin film of $FA\mathrm{Pb}{\mathrm{Br}}₃$, a metal halide perovskite used in transparent photovoltaics and light emitters. Photoluminescence (PL) at low excitation intensity and low temperatures only shows the free-exciton (FE) signal. As the excitation intensity increases, two additional signals in PL emerge: the electron-hole plasma (EHP) and the EHL recombination bands. For both the FE-EHP and the EHP-EHL phase transitions, a critical carrier density is established and a phase diagram is presented.