Optical properties of nanocrystal films: blue shifted transitions as signature of strong coupling
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AuthorSkibinsky Gitlin, Erik S.; Rodríguez Bolívar, Salvador; Califano, Marco; Gómez Campos, Francisco Manuel
Royal Society of Chemistry
Skibinsky-Gitlin, E. S., Rodríguez-Bolívar, S., Califano, M., & Gómez-Campos, F. M. (2020). Optical properties of nanocrystal films: blue shifted transitions as signature of strong coupling. Nanoscale Adv., 2020, 2, 384
SponsorshipM. C. gratefully acknowledges financial support from the School of Electronic & Electrical Engineering, University of Leeds. F. M. G. C. and S. R. B. were supported by Project ENE2016_80944_R, funded by the Spanish Ministerio de Econom´ıa, Industria y Competitividad.
We present a theoretical study at the atomistic level of the optical properties of semiconductor nanocrystal films. We investigate the dependence of the absorption coefficient on size, inter-dot separation, surface stoichiometry and morphology, temperature, position of the Fermi level and light polarization. Our results show that, counter-intuitively, huge blue shifts are expected in some intra-band transitions for strongly coupled arrays, in contrast with the predicted and observed red shift of the band gap absorption in such systems. Furthermore, we find that the energies of such transitions can be tuned within a range of several hundreds of meV, just by engineering the inter-dot separation in the film through the choice of appropriately sized capping ligands. Finally we discuss the application of this effect to nanocrystalbased intermediate-band solar cells.