Distinguishing between dynamical and static Rashba effects in hybrid perovskite nanocrystals using transient absorption spectroscopy

Yuri D. Glinka, Rui Cai, Junzi Li, Xiaodong Lin, Bing Xu, Kai Wang, Rui Chen, Tingchao He, Xiao Wei Sun

Sep 12, 2019
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Received Date: 22nd August 19

The dynamical and static Rashba effects in hybrid methylammonium (MA) lead halide perovskites have recently been theoretically predicted. However, only the static effect was experimentally confirmed so far. Here we report on the dynamical Rashba effect observed using snapshot transient absorption spectral imaging with 400 nm pumping for a fully encapsulated film of ~20-nm-sized 3D MAPbBr3 nanocrystals. The effect causes a ~240 meV splitting of the lowest-energy absorption bleaching band, initially appearing over sub-ps timescale and progressively stabilizing to ~60 meV during ~500 ps. The integrated intensities of the split subbands demonstrate a photon-helicity-dependent asymmetry, thus proving the Rashba-type splitting and providing direct experimental evidence for the Rashba spin-split edge states in lead halide perovskite materials. The ultrafast dynamics is governed by the relaxation of two-photon-excited electrons in the Rashba spin-split system caused by a “built-in” electric field originating from dynamical charge separation in the entire MAPbBr3 nanocrystal.

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This is an abstract of a preprint hosted on an independent third party site. It has not been peer reviewed but is currently under consideration at Nature Communications.

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