With
the advancement of solid-state lighting technology, the design
and preparation of fluorescence conversion films have become increasingly
important. RE2(OH)5NO3·nH2O is a popular building block in constructing
multifunctional films. In this paper, an electrodeposition method
is developed to prepare RE2(OH)5NO3·nH2O films within 10 min, avoiding
the problems of long-time consumption and low yield of the available
four-step method. The study of anion exchange of RE2(OH)5NO3·nH2O found
that the higher concentration difference between the anion source
Na2MoO4 and RE2(OH)5NO3·nH2O promotes the exchange
of interlayer NO3
– and ligands (hydroxyl
and water) in the [RE2(OH)5(H2O)
n
]+ main layer with MoO4
2–, and forms tetragonal-structured NaRE(MoO4)2 film at pH ∼7 and 150 °C. Due to
the fluorescence quenching groups in RE2(OH)5NO3·nH2O structure were exchanged by MoO4
2–, the intensity of Eu3+ emission
(5D0 → 7F2) for
NaEu(MoO4)2 film is ∼10 times that of
Eu2(OH)5NO3·nH2O
film under excitation at 394 nm. In addition, the films exhibit multicolor
luminescence and long fluorescence lifetime by doping activators (Eu3+ and Tb3+) into the NaLa(MoO4)2 lattice and adjusting the molar ratio of activators, making
them promising color-conversion films for solid-state lighting. This
work offers a new concept for the design and fabrication of NaRE(MoO4)2 films, and it might be extended to other kinds
of functional films.