We comparatively analyze experimental and computational vibrational spectra to understand the mechanism leading to high temperature, broadband light emission from hybrid self-assembled perovskite-like quantum wells. Following the fast formation of alkyl- and aryl-spaced lead iodide quantum well superlattices, we observe significant light emission 1 eV below these materials’ optical gaps whose width spans more than 0.1 eV. Most interestingly, the intensity of this emission is modulated at frequencies in the range of material vibrations. We use experimental spontaneous and density functional theory computational Raman spectra to propose molecular cations trap excitons and cause broadband light emission. We discuss this possibility in the context of previous studies proposing broadband light emission features in similar materials result from structural defects in the lead iodide octahedra. These results demonstrate the necessity of merging experimental and theoretical vibrational spectroscopic techniques to understand the photo-physical properties of self-assembled nano-materials central to their application in next generation opto-electronic technologies.

Molecular vibrational signatures of exciton trapping in self-assembled hybrid organic-inorganic quantum nanostructures

2019 Spring National Meeting

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