Solvothermal synthesis and characterization of highly monodisperse organically functionalized vanadium oxide nanocrystals for thermochromic applications

Abstract

We report on the synthesis and characterization of highly monodisperse organically functionalized vanadium oxide (VOx) nanocrystals with a size of 7-10 nm. We show that how these nanocrystals can be prepared by an improved solvothermal reaction and confirm their composition and structure through various materials characterization techniques. Our results revealed that VOx nanocrystals have a crystalline structure almost identical to that of paramontroseite VO2(P) and the majority of vanadium is in oxidation state of V(IV). VOx nanocrystal films can be readily prepared via a spin coating technique. Once thermally annealed at similar to 350 degrees C under an air/N-2 flow, the films exhibited good thermochromic properties (luminous transmittance (Th-lum) approximate to 49-66%, infrared switching efficiency (Delta T-2000nm) approximate to 28-43%, and solar modulating ability (Delta T-sol) approximate to 7.4-10.7%), corresponding to a phase transition between monoclinic VO2(M) and rutile VO2(R).