Semiconductor Nanocrystals as Triplet Sensitizers
Abstract
Three semiconductor nanoscale materials, CdSe, PbS, and halide perovskites (L2PbX4 and CsPbX3) will be prepared in solution and investigated in conjunction with molecular organic chromophores appended to their surfaces. These molecules include aromatic hydrocarbons as well as naphthalene and perylene mono- and diimides. These chromophores are synthetically versatile, photochemically stable, and possess singlet and triplet energies spanning the visible and near-IR regions of the spectrum; ideal candidates for coupling with the proposed semiconductor nanomaterials to quantitatively evaluate energy transfer phenomena from nanocrystals to molecules. Detailed understanding of triplet energy transfer/migration mechanisms and their quantum efficiencies will be determined using a battery of static and dynamic (ultrafast to millisecond) spectroscopic techniques including photoluminescence, absorbance, and infrared. CdSe and PbS nanocrystals will be prepared with systematically variable size; these materials exhibit classic quantum confinement where the relevant exciton energies predictably increase with decreasing size. Therefore, triplet energy transfer kinetics will be methodically studied as a function of CdSe and PbS quantum dot diameter/energy with each type of appended organic chromophore. These studies will enable determination of operable energy transfer mechanism(s) and critical intermediates will be characterized and assigned. Reverse triplet energy transfer from the appended chromophore to the quantum dot will be investigated using both transient absorption and photoluminescence techniques. Energetics in CsPbX3 nanocrystals and L2PbX4 nanoplatelets will be coarsely tuned by changing the halide (X). Variation from Cl- to Br- to I- renders materials from high to low energy, respectively, which are finely adjusted through blending the halide composition. Molecular organic chromophores will be introduced as either amine-terminated species (CsPbX3),,,
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 30, 2018
- Source ID
- FA95501810331
Entities
People
- Felix Castellano
Organizations
- Air Force Office of Scientific Research
- North Carolina State University
- United States Air Force