posted on 2024-03-06, 00:44authored byJonathan Zerhoch, Stanislav Bodnar, James E. Lerpinière, Shangpu Liu, Timo Neumann, Barbara Sergl, Markus W. Heindl, Andrii Shcherbakov, Ahmed Elghandour, Rüdiger Klingeler, Alison B. Walker, Felix Deschler
Spin–orbit coupling in the electronic states of
solution-processed
hybrid metal halide perovskites forms complex spin-textures in the
band structures and allows for optical manipulation of the excited
state spin-polarizations. Here, we report that motional narrowing
acts on the photoexcited spin-polarization in CH3NH3PbBr3 thin films, which are doped at percentage-level
with Mn2+ ions. Using ultrafast circularly polarized broadband
transient absorption spectroscopy at cryogenic temperatures, we investigate
the spin population dynamics in these doped hybrid perovskites and
find that spin relaxation lifetimes are increased by a factor of 3
compared to those of undoped materials. Using quantitative analysis
of the photoexcitation cooling processes, we reveal increased carrier
scattering rates in the doped perovskites as the fundamental mechanism
driving spin-polarization-maintaining motional narrowing. Our work
reports transition-metal doping as a concept to extend spin lifetimes
of hybrid perovskites.