Chromogenic properties of nanostructured periodic and non-periodic transition metal oxide thin films for optical and photonic applications

本研究的目的是将过渡金属氧化物（TMO）薄膜的显色特性和周期性和非周期性纳米结构结合起来，以提高其性能。TMO薄膜由于具有多种氧化态和特殊的结构而表现出多种显色性能。它们在外电场（电致变色）、热（热致变色）和光（光致变色）的影响下可逆地改变其光学性质的能力被称为显色性。这种显色性能在很大程度上取决于薄膜的纳米结构，它能诱导出有效着色和漂白所需的有利特性。因此，本文提出的主要目标是建立薄膜纳米结构与显色性能之间的相关性。实验工作将集中在薄膜制备方法上，以诱导精确的纳米结构，并表征各种外部影响下的显色性能。将进行深入的理论建模工作，以理解显色现象的潜在物理，特别是与纳米结构材料有关的现象。周期性和非周期性纳米结构TMO薄膜将被研究。从本研究中获得的知识将用于提高薄膜的光学和光子性能。从增强光学性能的角度来看，非周期结构非常有趣，而周期结构因其选择性操纵光传播（通过光子带隙）的独特能力而非常重要。光子带隙的可逆和连续调谐是要进行的工作的核心。因此，这两种情况的最终目标都是实现对各种应用（如智能窗口、传感器和光学电路）中重要的光学和光子特性的交互式外部控制。评估基于这些纳米结构TMO薄膜的光学和光子器件的应用潜力将是工作中需要解决的一个重要方面。

The objective of the proposed research is to bring together the fields and virtues of 1) Chromogenic properties of transition metal oxide (TMO) thin films and 2) periodic and non-periodic nanostructuring of these thin films to enhance their properties. TMO thin films exhibit various kinds of chromogenic properties due to their multiple oxidation states and their special structure. Their ability to reversibly change their optical properties under the influence of external electric field (electrochromics), heat (thermochromics) and light (photochromics) is termed chromogenics. This chromogenic performance is found to depend very strongly on the film nanostructure which induces favourable traits required for efficient coloration and bleaching. Hence, the main goal of the work proposed is to establish the correlation between the film nanostructure and the chromogenic performance. The experimental work will focus on the thin film preparation methodology to induce the precise nanostructure and to characterize the chromogenic properties under various external influences. In-depth theoretical modelling work will be undertaken to comprehend the underlying physics of the chromogenci phenomena especially as it relates to nanostructured materials. Both periodically and non-periodically nanostructured TMO thin films will be studied. The knowledge gained from this research will be applied towards enhancing the optical and photonic perforamnce of the films. The non-periodic structures are very interesting from the point of view of their enhanced optical performance while the periodic structures are important for their unique ability to selectively manipulate light propagation (through photonic bandgap). The reversible and continuous tuning of the photonic band gap is at the heart of the work to be undertaken. Hence, the ultimate goal in both the cases is to achieve an interactive external control of optical and photonic properties of importance in various applications such as smart windows, sensors and optical circuitry. Evaluation of the application potential of the optical and photonic devices based on these nanostructured TMO thin films will be an important aspect to be addressed in the work.