Excitation wavelength dependent photon emission and phase change probing in CsPbBr3 quantum dots

Inorganic lead halide perovskites such as CsPbBr3 exhibit tremendous potential for use in optoelectronic and radiation detection devices. This experimental work on CsPbBr3 Quantum Dots (QD) seeks to explore and report on the physics behind their response to photoexcitation using two different laser wavelengths. One of the excitation wavelengths photoexcites the electron deeper into the conduction band while the other slightly above the reported bandgap. Photoluminescence spectra from the sample show a contrasting behavior, both in terms of emission wavelengths and probing of the widely known phase change behavior in these material systems. While the former is tentatively attributed to what the dominant structural phase is, we speculate that the latter is due to a change in the energy band structure (with a corresponding change in optical transitions) of the system as it transitions from an orthorhombic phase to a tetragonal one.