Scheelite-structure tungstates with unique structural features and excellent luminescence possess promising applications, such as light-emitting diodes (LEDs), scintillators, and displays. The controllable growth of high quality and uniform composition thin films mounted on cheap substrates is a key factor to realize the above commercial applications, however, which is also a big challenge due to the difficult stress release stemming from intrinsic lattice mismatches. Here, we employed the simple and composition-controlled polymer-assisted deposition (PAD) method to successfully obtain a series of high quality and well-proportioned BaWO₄:Eu³⁺ (BWOE) thin films with red emission. Screening out the unbound freedom metal ions by poly(ether imide) (PEI) and ethylene diamine tetraacetic acid (EDTA), the firmly bound metal ions (Ba²⁺, W⁶⁺ and Eu³⁺) in polymer solution were applied to accurately control the chemical composition and effectively governed the release of stress during the growth process of BWOE thin films. Furthermore, XRD, SEM and EDS mapping detections evidently authenticated the quasi-single crystallinity, uniform morphology and well-distributed composition of as-grown thin films. Additionally, excited by 250 nm light, these thin films could efficiently produce the red emission, peaked at around 612 nm originated from the ⁵D₀ → ⁷F₂ transition of Eu³⁺. Moreover, the optimal doping concentration of thin films was confirmed to be 9% and corresponding Commission International de l’Eclairage (CIE) chromaticity coordinate was (0.618, 0.365), which evidently implied the excellent color rending index. Therefore, this work highlights the rather superior PAD method to prepare uniform and high-quality BWOE thin films, which can be expanded toward the other photoelectric devices including white lighted-emitting diodes, scintillators, displays, and photoelectric detectors.

中文翻译：

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掺杂Eu ^3+的单晶BaWO ₄薄膜的结构和光学研究

具有独特结构特征和优异发光性能的白钨矿结构钨酸盐具有广阔的应用前景，例如发光二极管（LED），闪烁体和显示器。安装在廉价基板上的高质量和均匀组成的薄膜的可控生长是实现上述商业应用的关键因素，然而，由于固有的晶格失配导致难以释放应力，这也是一个巨大的挑战。在这里，我们采用了简单且受组成控制的聚合物辅助沉积（PAD）方法，成功获得了一系列高质量且比例合理的BaWO ₄：Eu ³⁺（BWOE）具有红色发射的薄膜。通过聚醚酰亚胺（PEI）和乙二胺四乙酸（EDTA）筛选出未结合的自由金属离子，将聚合物溶液中牢固结合的金属离子（Ba 2 ⁺，W ⁶⁺和Eu ³⁺）准确地应用于在BWOE薄膜的生长过程中控制化学成分并有效控制应力的释放。此外，XRD，SEM和EDS映射检测明显地证明了成膜薄膜的准单晶性，均匀的形态和分布均匀的成分。此外，在250 nm的光激发下，这些薄膜可以有效地产生红色发射，其峰值起源于⁵ D ₀ →在612 nm左右→Eu ^3+的7 F ₂跃迁。此外，确定薄膜的最佳掺杂浓度为9％，相应的国际照明委员会（CIE）色度坐标为（0.618，0.365），这显然暗示了优异的显色指数。因此，这项工作突出了制备均匀且高质量的BWOE薄膜的相当优越的PAD方法，该方法可以扩展到其他光电器件，包括发白光的二极管，闪烁体，显示器和光电探测器。