Layered lead halide perovskites have attracted much attention
as
promising materials for a new generation of optoelectronic devices.
To make progress in applications, a full understanding of the basic
properties is essential. Here, we study 2D-layered (BA)2PbX4 by using different halide anions (X = I, Br, and
Cl) along with quantum confinement. The obtained cell parameter evolution,
supported by experimental measurements and theoretical calculations,
indicates strong lattice distortions of the metal halide octahedra,
breaking the local inversion symmetry in (BA)2PbCl4, which strongly correlates with a pronounced Rashba spin-splitting
effect. Optical measurements reveal strong photoluminescence quenching
and a drastic reduction in the PL quantum yield in this larger band
gap compound. We suggest that these optical results are closely related
to the appearance of the Rashba effect due to the existence of a local
electric dipole. The results obtained in ab initio calculations showed
that the (BA)2PbCl4 possesses electrical polarization
of 0.13 μC/cm2 and spin-splitting energy of about
40 meV. Our work establishes that local octahedra distortions induce
Rashba spin splitting, which explains why obtaining UV-emitting materials
with high PLQY is a big challenge.