Deviatoric Stress-Induced Transition of Self-Trapped Exciton Emissions

Abstract Self-trapped exciton (STE) emissions, featured by their broad spectral band and little self-absorption, have garnered considerable attention for advanced lighting and imaging applications. However, the exploration of an effective strategy to facilitate multiple STE states, modulate the emission energy and the cover range remains a great challenge. Here, we introduce deviatoric stress, facilitating an extrinsic STE (ex-STE) state and the transition between ex-STE and another intrinsic STE (in-STE) emissions in pyramidal ZnO nanocrystals, achieving a remarkable transition of emission energy from yellow-green (2.34 eV) to deep-blue (2.88 eV). Combined in-situ stress monitoring and optical experiments demonstrate that the ex-STE state originates from a potential well generated by plastic deviatoric deformation induced by deviatoric stress. Spectroscopic and dynamical characterization of these two STE emissions reveal a transition process in the carrier’s relaxation pathway from ex-STE to in-STE, and conversely at much higher pressure. These findings demonstrate that deviatoric stress is a robust tool to drive STE emissions and provide deep insights into the carrier dynamics evolution of STE emissions.