During the last years, giant optical anisotropy has demonstrated
its paramount importance for light manipulation. In spite of recent
advances in the field, the achievement of continuous tunability of
optical anisotropy remains an outstanding challenge. Here, we present
a solution to the problem through the chemical alteration of halogen
atoms in single-crystal halide perovskites. As a result, we manage
to continually modify the optical anisotropy by 0.14. We also discover
that the halide perovskite can demonstrate optical anisotropy up to
0.6 in the visible rangethe largest value among non-van der
Waals materials. Moreover, our results reveal that this anisotropy
could be in-plane and out-of-plane depending on perovskite shaperectangular
and square. As a practical demonstration, we have created perovskite
anisotropic nanowaveguides and shown a significant impact of anisotropy
on high-order guiding modes. These findings pave the way for halide
perovskites as a next-generation platform for tunable anisotropic
photonics.
Halide perovskites have demonstrated great potential for photovoltaics and detector applications, due to the strong absorption, large mobility lifetime product, structural defect tolerance, and wide range of chemical compositions with...
We present an experimental investigation of methylammonium lead tribromide single crystals in the orthorhombic, tetragonal, and cubic phases based on inelastic and deep inelastic neutron scattering experiments. We show how the average hydrogen nuclear kinetic energy, mainly affected by zero-point vibrational energies, shows differences larger compared to the changes simply related to temperature effects when moving from one phase to another. In particular, the Gaussian contribution to the average nuclear kinetic energy is larger in the tetragonal phase compared to the cubic and orthorhombic ones. Moreover, we find that the vibrational densities of states of MAPbBr3 single crystals in the orthorhombic phase are compatible with previously reported results on powder samples, and that the only vibrational modes that show slightly different frequencies compared to MAPbI3 are those in the energy range between 100 and 300 cm-1, related to librational/rotational modes. As these shifts are of about 10 cm-1, and do not affect any higher-energy vibrational mode, we conclude that the zero-point energies and average nuclear kinetic energies in the two-hybrid organic/inorganic perovskites are expected to be approximately the same within a harmonic framework.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.