Fig. 6: Calculation of exciton polaron in 2D metal halide perovskites.
From: Robust excitonic light emission in 2D tin halide perovskites by weak excited state polaronic effect
Scheme of potential energy surface labeled with ground state (GS), excited state (ES) and Urbach exciton (UE) states of (a) (PEA)2(MA)Sn2I7 and (b) its Pb counterpart. c Illustrations of inter-octahedron distortion and the corresponding distortion descriptors including length displacement (\({L}_{{{\rm{d}}}}\)) and angle deviation (\({\theta }_{{{\rm{d}}}}\)) in octahedral layers along a-b direction. The arrows denote the movement direction of the iodine atoms. The calculated (d) \({L}_{{{\rm{d}}}}\) and (e) \({\theta }_{{{\rm{d}}}}\) of (PEA)2(MA)Sn2I7 and (PEA)2(MA)Pb2I7 (labeled as Sn and Pb) in GS and ES configurations. DOS of ground-state and excited-state configurations in (f) (PEA)2(MA)Sn2I7 and (g) its Pb counterpart. h Summed electron (hole) densities in a-b plane (\({\rho }_{i}\left(z\right)\)) as a function of z coordinate. i Effective distance between electron and hole along z coordinate in ground-state and excited-state configurations of (PEA)2(MA)Sn2I7 and its Pb counterpart.
