Circular Dichroism Studies of Spin Dynamics in 4-Aminomethyl Piperidinium Methyl Ammonium Lead Iodide Perovskite Quantum Wells

Abstract

Two dimensional perovskites are planes of perovskite octahedra confined by an organic spacing layer, making a multiple quantum well structure. The structure of the organic spacing molecule causes distortions to the perovskite sheet which impacts the electronic and optoelectronic properties of the material. Using pump probe circular dichroism the spin dynamics of the 2D perovskite (4AMP)MAPb2I7 are reported and compared to a material with the same perovskite sheet but a different spacing molecule ((BA)MAPb2I7). The spin lifetime in 4AMP was found to be 15 ps and decreased with increasing excitation energy, consistent with BA. It was found that the spin lifetimes in 4AMP had no dependence on carrier density over two orders of magnitude, contrary to BA. This is attributed to the lack of out-of-plane tilting in 4AMP, which leads to a suppression of the precessional spin relaxation in this material.