Modulation of Auger recombination via facet engineering in CsPbBr3 perovskite nanocrystals

Abstract

We present a mechanistic study of harnessing Auger suppression through a strategy of facet engineering on two contrasting perovskite systems of facet-controlled CsPbBr₃ nanocrystals (CPB NCs), i.e., dodecahedron CPB (d-CPB) NCs vs. cubic CPB (c-CPB) NCs. It is found that d-CPB achieves a better suppression of Auger recombination than c-CPB. We employe ultrafast transient absorption spectroscopy, photoluminescence spectroscopy and spectroscopic ellipsometry to interrogate the underlying mechanisms from multiple perspectives, mainly addressing the volume scaling, dielectric screening and polaronic effects. The static dielectric screening effect is revealed to prevail over the dynamic polaronic screening effect. Compared to c-CPB NCs featuring nonpolar facets, d-CPB NCs featuring polar facets exhibit an elevated dielectric response (in the optical-frequency region) and strengthened screening of electron–hole Coulomb interaction, which accounts for the observed improvement in Auger suppression. As a proof of principle, the achieved modulation of Auger recombination via facet engineering is successfully materialized by a set of performance tests on c-CPB/d-CPB NC-based light-emitting diodes.