Enhanced Spin-Orbit Coupled Photoluminescence of Perovskite CsPbBr Quantum Dots by Piezo-Phototronic Effect.

Piezo-phototronic effect is a fundamental effect of semiconductors lacking of central symmetry with geometries from one-dimensional (1D) nanowire to 3D bulk. Here, we present that the piezo-phototronic effect can even tune a spin-orbit coupled photoluminescence (PL) based on all-inorganic perovskite CsPbBr quantum dots (QDs). Although the cubic structure of CsPbBr QDs is nonpiezoelectric, a cooling treatment can change it to an orthorhombic structure, which is proven to possess a piezoelectric property. The spin-orbit coupled PL intensity is demonstrated to be dependent on the polarization of the excited light. Because of the manipulation of the spin-split energy levels via the piezo-phototronic effect, the spin-orbit coupled PL intensities under a -0.9% compressive strain for linearly and circularly polarized light excitations can be enhanced by 136% and 146%, respectively. These findings reveal fundamental understandings of the spin-orbit coupled PL dynamics and demonstrate promising optoelectronic applications of the piezo-phototronic effect in these QDs.