Nanosheet Seed-Layer Assists Oriented Growth of Highly Luminescent Perovskite Films

Abstract

Oxide phosphors are attractive materials for various applications in optoelectronic devices due to their high chemical stability and efficient luminescent characteristics. As yet, however, the fabrication of high-quality luminescent thin films on a glass substrate remains challenging for practical implementation. Here, we report the efficient fabrication of highly oriented luminescent perovskite oxide films on a glass substrate using a monolayer film of oxide nanosheets as the seed layer. A densely packed monolayer film of Ca2Nb3O10 nanosheets was prepared by the Langmuir−Blodgett (LB) method, where hybridization of the cationic molecules and the Ca2Nb3O10 nanosheets produced stable LB films with large-area processability. Oriented thin films with a sharp and intense emission of Pr0.002(Ca0.6Sr0.4)0.997TiO3 were successfully obtained on a glass substrate modified with a seed layer. Highly luminescent transparent films are producible on inexpensive noncrystalline substrates; this approach also enables large-area processing of high-quality thin-film phosphors.

Langmuir and Langmuir-Blodgett Films of Organic Dye-Inorganic Nanosheet Hybrids

“…Lu et al [5] unambiguously showed that the stretching mode of the terminating Nb-O bond in a polyoxoanion NbW 3 second highest antisymmetric modes reaches 1.39, being unacceptably larger than 956/791 (the present experimental data). In addition, it is not obvious whether introduction of double bonds decreases this energy ratio.…”

“…3 and used as the "mother" suspension. This mother suspension was diluted to 4.0  10 -3 g L -1 by adding pure water with a resistivity higher than 1.8  10 7 cm provided by a Millipore Milli-Q system in order to be used as the subphase in the LB technique.…”

“…Among the inorganic nanosheets, Ca 2 Nb 3 O 5 -(CNO) nanosheets have been attracting special interests because a film of them deposited on a glass substrate works as an excellent seed layer in epitaxial growth of a Ca 0.6 Sr 0.4 TiO 3 :Pr phosphor film [3]. The apparent photo-luminescence exhibited by the oxide film grown on CNO nanosheets reflected its good crystallinity unambiguously.…”

La0.90Dy0.05Nb2O7 nanosheet phosphor and its multilayer films with enhanced host excitation-mediated photoluminescence

“…The residue after the post-treatments was curtained as ammonium and/or oxonium ions in the intersheet galleries, along with some water molecules [3,19,31]. The broad peaks may be related with the misalignment of the nanosheet crystallites [20]. Such polymer-free multilayer films of La 0.90 Dy 0.05 Nb 2 O 7 nanosheets allow us to perform the following PL experiments to avoid the possible interference with the intercalated polymer.…”

“…In particular, it is attractive to use them to fabricate multilayer composite films on a glass substrate through the layer-by-layer (LBL) assembly technology, based on the alternate adsorption with suitable polymeric cations [18][19][20][21][22][23][24]. After followed by ultraviolet light exposure or heat treatment, the organic cations will be decomposed completely, which leads to the formation of transparent polymer-free nanosheet multilayer films deposited on the substrate [22][23][24].…”