Emergent Electronic and Dielectric Properties of Interacting Nanoparticles at Finite Temperature*

Lead chalcogenide nanoparticle (NP) solids have been successfully integrated into certified solar cells and represent promising platforms for the design of novel photoabsorbers for photo-electrochemical cells. While much attention has been drawn to improving efficiency and device performance through altering the character of the individual NPs, the role of interactions between NPs is not yet well understood. Using first-principles molecular dynamics and electronic structure calculations [1], we investigated the combined effect of temperature and interaction on functionalized lead chalcogenide NPs. We show that at finite temperature, interacting NPs are dynamical dipolar systems, with average values of dipole moments and polarizabilities substantially increased with respect to those of the isolated building blocks. In addition, we show that the interacting NPs exhibit slightly smaller fundamental gaps that decrease as a function of temperature, and that the radiative lifetimes of both isolated NPs and the solids are greatly reduced at finite temperature compared to T=0.

[1] www.qboxcode.org