Michael Brennan

Chemistry and Biochemistry

Faculty Advisor: Dr. Masaru Kuno

Compositionally Insensitive Size-Dependent StokesShifts in CsPbX3 (X = Cl, Br, I) Nanocrystals

CsPbX3 (X = Cl, Br, I) nanocrystals are highly attractive materials to be implemented in next-generation light-emitting/harvesting applications due their tunable bandgaps, high photoluminescence quantum yields and narrow emission linewidths. Full elucidation of their size-dependent electronic/optical properties is critical to their successful implementation into working, efficient solar cells. In the proposed work, size-dependent Stokes shifts will be demonstrated to be universal features of colloidal all-inorganic lead halide perovskite (CsPbX3; X = Cl, Br, I) nanocrystals. We previously demonstrated size-dependent Stokes shifts exists in CsPbBr3 nanocrystals and have proposed a model so as to explain the phenomena’s origin (Brennan, M.C.; Herr, J.E.; et al. J. Am. Chem. Soc. 2017, 139, 12201-12208.; Brennan M.C.; et al. ACS Energy Lett. 2017, 2, 1487- 1488.) Our modeling predicts size-dependent Stokes shifts will exist in CsPbX3 irrespective of their halide composition. This will be done by first synthesizing a size-series of high quality, monodisperse CsPbCl3, CsPb (Cl0.5Br0.5)3, CsPbI3 and CsPb(I0.5Br0.5)3 nanocrystals and subsequently measuring absorption/emission to determine Stokes shift values. Subsequent modeling of all aforementioned halide composition will accompany the experimental data. At a broader level, proving this phenomena is a general feature of all perovskite NCs will allow it to be tuned via NC size to influence their response within photovoltaic or light-emitting applications.