Fabrication of Nd3+-free Near Infra-Red (808 nm) Responsive Self-Sensitized Upconverting Nanocrystal with Enhanced Red Emission

Abstract

In recent times, 980 nm-responsive NIR-upconverting crystalline nanoparticles have found extensive application in the field of biomedicine. However, due to the strong water absorption profile of 980 nm excitation, the concerned upconverting nanoparticle (UCNP) suffer from heating effect. Also, Nd3+ sensitized 808 nm excitation had weak intensity and thus in order to improve UCL efficiency, core-shell structured UCNPs were designed, in which activator and Nd3+ were doped in inner core and outer shell, respectively, in order to minimize the cross relaxation. In this work, a pathway for developing 808 nm-responsive core UCNP with intense and diversified emission profile is described. Apart from synthesizing the UCNP with enhanced emission profile, a thorough characterization of the crystalline structure at the local level has been proposed. Detailed mechanism behind the intensification of the emission profile is to be investigated using exhaustive synchrotron X-ray diffraction study. Finally, the superior photodynamic activity of the proposed UCNP with enhanced emission profile is to be validated through few basic applications. The proposed work is expected to gather fundamental knowledge on crystal engineering-based nanotechnology.