Charge Carrier Dynamics in Bulk and 2D Perovskites Semiconductors

The effect of carrier-carrier and carrier-phonon interactions is presented in (n=1)(2D) (BA)2PbI4 Ruddlesden-Popper thin films compared to that of conventional bulk MAPbI3(n=infinity). The binding energy of excitons mediates the interaction with phonons. The strongly coupled excitons manifest themselves as small polarons that interact with lattice via the emission of LO-phonon replicas, while weakly bound excitons manifest themselves as large polarons and result in large LO-phonon broadening due to stronger carrier-phonon scattering. These results suggest that the hot carrier thermalization in perovskites is dominated by the strength and nature of the exciton-phonon interaction. To support this hypothesis, comparisons of hot carrier dynamics and electron-phonon interactions in transient absorption and CW PL are made on a number of stable and well-studied perovskite thin films (FAPbI3, FAPbBr3, and FAMASnPbI).