Liu, Yun Kim, Donghun Morris, Owen P. Zhitomirsky, David Grossman, Jeffrey C. 2024-01-19T23:30:45Z 2024-01-19T23:30:45Z 2021-09-03 2018-03 1936-0851 https://pubs.kist.re.kr/handle/201004/121683 Understanding the origins of the excessive Stokes shift in the lead chalcogenides family of colloidal quantum dots (CQDs) is of great importance at both the fundamental and applied levels; however, our current understanding is far from satisfactory. Here, utilizing a combination of ab initio computations and UV-vis and photoluminescence measurements, we investigated the contributions to the Stokes shift from polydispersity, ligands, and defects in PbS CQDs. The key results are as follows: (1) The size and energetic disorder of a polydisperse CQD film increase the Stokes shift by 20 to 50 meV compared to that of an isolated CQD; (2) Franck-Condon (FC) shifts increase as the electronegativities of the ligands increase, but the variations are small (<15 meV). (3) Unlike the aforementioned two minor factors, the presence of certain intrinsic defects such as V-Cl(+) (in Cl-passivated CQDs) can cause substantial electron density localization of the band edge states and consequent large FC shifts (100s of meV). This effect arising from defects can explain the excessive Stokes shifts in PbS CQDs and improve our understanding of the optical properties of PbS CQDs. English AMER CHEMICAL SOC TOTAL-ENERGY CALCULATIONS WAVE BASIS-SET SEMICONDUCTOR NANOCRYSTALS SOLAR-CELLS SIZE SOLIDS EXCITON EMISSION EXCHANGE STATES Origins of the Stokes Shift in PbS Quantum Dots: Impact of Polydispersity, Ligands, and Defects Article 10.1021/acsnano.8b00132 1 ACS NANO, v.12, no.3, pp.2838 - 2845 ACS NANO 12 3 2838 2845 scie scopus 000428972600078 2-s2.0-85044526955 Chemistry, Multidisciplinary Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Chemistry Science & Technology - Other Topics Materials Science Article TOTAL-ENERGY CALCULATIONS WAVE BASIS-SET SEMICONDUCTOR NANOCRYSTALS SOLAR-CELLS SIZE SOLIDS EXCITON EMISSION EXCHANGE STATES PbS nanocrystal colloidal quantum dot DFT Stokes shift defects