Lifetime-ultra-prolonged luminescent multilayer thin films with electronic microenvironment

Abstract

EME's architecture assembled by oppositely-charged inorganic nanosheets is benefited for prolonging significantly the lifetimes of multilayer thin films.

Synthesis and Characterization of La-Doped Luminescent Multilayer Films

“…The fluorescence lifetime analysis (Table 1) first reason is the rigid structure's IE, stopping the aggregation, and formation of BNMA. But the most important one of all is that EM can be formed by the positive LDHs nanosheets and negative MMT nanosheets, which can affect the vibration of backbone so that it can prolong the lifetimes of the films [28]. At the same time, we selected CoAlLa-LDHs and BNMA to assemble the luminescent thin films via LBL method, in order to generate the FE between the interlayers.…”

“…The La-doped LDHs were synthesized via coprecipitation method, similar to our previous work [28]. Typically, divalent metallic cations M 2+ (Mg 2+ or Co 2+ ) and trivalent metallic cations M 3+ (Al 3+ , La 3+ ) were mixed in boiled deionized water (M 2+ /M 3+ = 2 and Al 3+ /La 3+ = 1).…”

“…At the same time, isomorphous replacement of certain M 2+ cations by M 3+ cations in LDHs, such as Al 3+ and Ga 3+ , gives positively charged layers, and montmorillonite's (MMT) nanosheets also process opposite charge due to different isomorphic substitution compared with LDHs [26,27]. In our previous work, it was testified that electronic microenvironment (EM) assembled by LDHs and MMT nanosheets can prolong the luminescent lifetimes of thin films [28]. Besides, when introducing transition metal on nanosheets, LDHs can be served as ferromagnetic layers.…”

Novel Luminescent Multilayer Films Containing π-Conjugated Anionic Polymer with Electronic Microenvironment

“…Then, centrifuge this turbid liquid at 10,000 rpm for 10 min in order to obtain a solution with exfoliated MMT nanosheets. Quartz slides were cleaned in H 2 SO 4 Figure 2a shows the UV-vis absorption spectra and photoluminescence spectra of MA(n)-films with varying numbers of layers (n = 4, 8,12,16,24,32), and the inset of left figure indicates the intensities of absorption peaks increase linearly at 293.5 nm and 452.5 nm when the layers grow, displaying a well-organized growth in assembly process of those thin films. Under 375 nm excitation, these thin films give a green emission band peak at 572.0 nm (Figure 2b).…”

“…Recently, our group has successfully verified that an electronic microenvironment (EME) can enhance the multilayer films' lifetimes containing cationic chromophores about 40-fold as long as those of the original powders [16]. Exfoliated LDHs and MMT nanosheets constructed a nano-system via LBL method, and then EME can be formed by the oppositely-charged rigid inorganic nanosheets between the interlayers, as shown in Figure 1.…”