Evidence of defect-induced broadband light emission from 2D Ag-Bi double perovskites grown at liquid-liquid interfaces.

Controlling the light emission spectra of low-dimensional hybrid organic-inorganic materials remains an important goal toward the implementation of these materials into real-world optoelectronic devices. In this study, we present evidence that the self-assembly of two-dimensional (2D) silver bismuth iodide double perovskite derivatives at the interface of aqueous and organic solutions leads to the formation of defects capable of modulating the light emission spectra of these materials. Through an analysis of the structural parameters used to explain the photoluminescence (PL) spectra of 2D perovskites, we show the light spectra emitted by (4-ammonium methyl)piperidinium (4-AMP) and (3-ammonium methyl)pyridinium (3-AMPy)-spaced AgBiI 8 double perovskites formed through interfacial solution-phase chemistry differ qualitatively and quantitatively from thin film samples. We use previous results to propose the differences observed in the PL spectra of different material morphologies stem from equatorial iodide vacancy formation driven by the kinetics of self-assembly at the liquid-liquid interface. These results show the generality of these chemical physics principles in the formation of defect sites in solution-processed semiconducting nanomaterials, which could help enable their broad use in optoelectronic technologies.