Nanophotonic energy storage in upconversion nanoparticles

Abstract

In nanophotonic energy storage, an energy conversion model is established for intrinsic nanophotonic energy storage (NPES) effects. Here we realize that the charge inhomogeneous distribution on the surface of upconversion nanoparticles (UCNPs) would persistently exist as well as the formation and migration of surface defects states despite of the compound component ratio, even following the stringent stoichiometric ratio. Our preliminary efforts on NPES effect has recognized from the recent published work by Chen et al. (2018) [4], in which the surface quantum confinement arose because of a recently found surface vacancy induced Coulomb states (SVIC) states. Further in-depth excavation on surface charge density distributions and defect orbitals of surface localized electrons and holes have affirmatively repeated the theory by Guerra et al. (2018) [32], and reflected the existence of surface defect states in both stoichiometric and non-stoichiometric compounds. Therefore, beyond the experimental trail-based multi-doping chemical modifications, we proposed that the surface electronic process for efficient NPES effect can be modulated by an intrinsic level-matching induced surface resonant quantum tunneling (LM-SRQT) in this work. The UCNP size-effect can be confirmed that simply might be not an influencing factor of dominating NPES effect while the surface degree of non-crystallizations indeed matters.