Observation of large Rashba spin–orbit coupling at room temperature in compositionally engineered perovskite single crystals and application in high performance photodetectors

Abstract

Indirect absorption extended below the direct transition edge and increase in carrier lifetime derived from Rashba spin-orbit coupling may advance the optoelectronic applications of metal halide perovskites. Spin-orbit coupling in halide perovskites is due to the presence of heavy elements in their structure. However, when these materials lack an inversion symmetry, for example by the application of strain, spin-orbit coupling becomes odd in the electron’s momentum giving rise to a splitting in the electronic energy bands. Here we report on the observation of a large Rashba splitting of 117 meV at room temperature through a facile compositional engineering approach in halide perovskite single crystals, as predicted by relativistic first-principles calculations. Partial substitution of organic cations by rubidium ions in single crystals induces significant indirect absorption and dual emission as a result of a large Rashba splitting. We measured significant magneto-photocurrent, magneto-electroluminescence and magneto-photoluminescence responses in perovskite single crystal devices and thin films. They originate from the significant spin-momentum locking that leads to different precession frequencies of their respective spins about the applied magnetic field. A hybrid perovskite single crystal photodetector achieved record figures of merit, including detectivity of more than 1.3×1018 Jones which represents a three orders of magnitude improvement compared to the to date record. These findings show that facile compositional engineering of perovskite single crystals holds great promise for further advancing the optoelectronic properties of existing materials.