Fig. 1: Characterization of pristine MAPbI3 and 2%Nd:MAPbI3 films.
From: Light-induced Kondo-like exciton-spin interaction in neodymium(II) doped hybrid perovskite
a XRD patterns of pristine MAPbI3 and 2%Nd:MAPbI3 thin films. The left inset is a schematic illustration of Pb2+ (green) substituted by Nd2+ (orange) in a perovskite octahedral framework, where I- is in purple and methylammonium (MA+) is in blue. The right inset is the magnified comparison for the peak at (110). b TEM images and SAED patterns of pristine MAPbI3 and 2%Nd:MAPbI3 thin films at r.t. (before cooling), 20 K and warmed back to r.t. (after cooling). c XPS comparison of Nd-3d for the Nd2+ in 2%Nd:MAPbI3 vs. Nd3+ in Nd(NO3)3 and Nd metal. Dashed lines are the fitted results. d UPS comparison of 2%Nd:MAPbI3 vs. pristine MAPbI3. e Temperature-dependent CW-EPR spectra of grinded powder of 2%Nd:MAPbI3. The dotted curves are the simulated results by Easy Spin. The intensities of all curves are offset for a better view. The inset is the proposed high spin (S = 2) electron configuration of Nd2+ (4f4) in an octahedral crystal field with I- being the weak ligand. Δ1 and Δ2 are the crystal field splitting energy between t2u and a2u energy levels, and between t1u and a2u energy levels, respectively.
