2e).Figure 2Īll the films were found amorphous from GIXRD investigation. All the processes showed excellent dependence of the film thickness on the number of ALD/MLD cycles (Fig. The gradual decrease in GPC with increasing deposition temperature seen for all the three processes is typical for nearly all ALD/MLD processes and is tentatively understood as an increased tendency of the organic precursors to desorb at higher temperatures. The dependence of the GPC on the deposition temperature was checked at three different temperatures (Fig. Similar trends were observed for NDA and ADA as well, the saturation reached with 8-s long organic precursor pulses (Fig. For the Eu-TP films, we scanned a broader range of TPA pulse lengths from 8 to 18 s and found out that an 8-s pulse was enough to achieve saturation. Then, the organic pulse lengths were optimized using the fully saturating Eu(thd) 3 pulse length from the former step. In each case, a 4-s pulse of Eu(thd) 3 was found sufficient for the surface saturation when a 12-s pulse of the organic precursor was used. The ALD/MLD processes, Eu(thd) 3 + TPA, Eu(thd) 3 + NDA and Eu(thd) 3 + ADA, for the growth of Eu-TP, Eu-ND and Eu-AD films were optimized, as shown in Fig. The samples were deposited on Si(100) substrates (25 x 25 mm 2). The reactor pressure was maintained between 5 and 10 mbar and nitrogen (> 99.999% Schmidlin UHPN 3000 N 2 generator) and was used both as the purging and carrier gas.

All depositions were carried out in a commercial flow-type hot-wall ALD reactor (F-120 by ASM Microchemistry Ltd.). The pulse lengths for Eu(thd) 3 as well as TPA, NDA and ADA were optimized to confirm self-saturating nature of the chemical reactions. The temperatures needed to evaporate TPA, NDA and ADA for the depositions were 185, 200 and 240 ☌, respectively. The organic precursors for the MLD step were commercial products: terephthalic acid (Tokyo Chemical Industry Co., Ltd.), 1,4-naphthalenedicarboxylic acid (NDA Sigma-Aldrich GmbH, Germany) and 9,10-anthracenedicarboxylic acid (Sigma-Aldrich GmbH, Germany). For the evaporation, the Eu(thd) 3 precursor was heated to 140 ☌ inside the reactor chamber. The europium precursor Eu(thd) 3 (thd = 2,2,6,6-tetramethyl-3,5-heptanedione) was synthesized in-house. However, so far, the literature lacks details about the influence of different organic moieties on the luminescence properties of metal-organic hybrid thin films. Compared to the inorganic luminescent thin films deposited using ALD, the ALD/MLD approach offers some additional benefits, such as material deposition on polymeric substrates for flexible devices and appreciably high growth rates. The technique has also been used to deposit Ln-based hybrid thin films, which have demonstrated interesting photoluminescence (down-shifting) and upconversion characteristics. for thermoelectric devices, lithium-ion batteries and catalysis. The metal-organic materials grown by ALD/MLD have already proven their potential, e.g. The thus grown hybrid thin films are precisely thickness-controlled, conformal and uniform over large-area and complex substrate surfaces, like the inorganic thin films deposited using the parent ALD technology. This enables, through self-limiting gas-surface chemical reactions, the growth of metal-organic materials with atomic/molecular level accuracy. In ALD/MLD, mutually reactive gaseous/vaporized metal-bearing and purely organic precursors are sequentially pulsed into the reactor chamber. atomic/molecular layer deposition (ALD/MLD), could open up new horizons to the field as it allows us to combine organic linkers to the Ln species. Moreover, the currently strongly emerging counterpart of ALD for hybrid metal-organic thin films, i.e. Atomic layer deposition (ALD) is the state-of-the-art thin film technology in microelectronics and in other high-tech industrial applications and would also intuitively fit to the quality needs of the inorganic Ln-based luminescent thin films, as well as modern photonic and quantum technologies. Conventional coating methods, such as spin coating and spray drying, suffer from the poor film thickness control and the unwanted incorporation of solvent impurities into the film. A majority of these applications require the luminescent material in the form of a thin film or coating. Lanthanide (Ln)-based luminescent materials exhibit all of the aforementioned photon conversion processes and can be implemented for a breadth of applications, such as solar cells, lasers, displays, lighting, sensors, bioimaging, disease diagnostics and therapy, (bio)chemical analysis and security tags.

Carbon backbone