Room-Temperature Broadband Light Emission from Hybrid Lead Iodide Perovskite-Like Quantum Wells: Terahertz Spectroscopic Investigation of Metastable Defects

J Phys Chem Lett. 2019 Apr 18;10(8):1653-1662. doi: 10.1021/acs.jpclett.9b00743. Epub 2019 Mar 27.


The properties of mid-band-gap electronic states are central to the potential application of self-assembled, hybrid organic-inorganic perovskite-like quantum wells in optoelectronic technologies. We investigate broadband light emission from mid-band-gap states in fast-forming hybrid organic lead iodide quantum wells at room temperature. By comparing temperature- and intensity-dependent photoluminescence (PL) spectra emitted from butyl ammonium spaced inorganic layers, we propose that structural defects in a metastable material phase trap excitons and cause broadband light emission spanning wavelengths between 600 and 1000 nm. We use temperature-dependent terahertz time-domain spectroscopy to correlate changes in the subgap PL emission with changes in the chemical bonding of the inorganic octahedral layer. Our results provide new fundamental physical insights into the array of mechanisms capable of inducing broadband light emission from low-dimensional perovskite-like materials central to their application in future optoelectronic technologies and novel spectroscopic tools to characterize these states.