液晶結合電致變色材料之光電特性及其調光調色之應用;Optoelectrical properties of liquid crystals combined with electrochromic materials for dimmer and color modulation applications

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/94968

Title:	液晶結合電致變色材料之光電特性及其調光調色之應用;Optoelectrical properties of liquid crystals combined with electrochromic materials for dimmer and color modulation applications
Authors:	黃智彙;Huang, Chih-Hui
Contributors:	光電科學與工程學系
Keywords:	電致變色;二色性染料;液晶摻雜離子;調光;調色;Electrochromism;Dichroic dye;Liquid crystal doped with ion;Smart dimming;Color modulation
Date:	2024-07-29
Issue Date:	2024-10-09 15:39:53 (UTC+8)
Publisher:	國立中央大學
Abstract:	一般而言，液晶技術多以染料摻雜和控制布拉格反射頻帶控制光吸收或變色，然而結合液晶與電致變色技術實現調光調色功能的研究並不多見，因此本研究主要探討將電致變色技與液晶技術結合，以創造兼具兩者優勢的新型顯示技術。首先，本研究嘗試以正型液晶E7摻雜離子鹽LiClO_4提供電致變色中氧化還原反應所需離子，結合電致變色層製成液晶電致變色元件，然而發現離子自發性垂直基板排列的問題導致造成液晶失去雙折射特性，因此本研究以負型液晶HNG30400-200取代正型液晶以解決該問題，並加入手性分子S811形成螺旋結構提升離子遷移效果，實現無色透明態、上色透明態、上色散射態及無色散射態等四種狀態，但依然存在操作電壓較大、顏色深度和均勻度不理想等問題。本研究接著針對電致變色性能進行提升，比較了三種離子液[Bmim][NTf2]、[Bmim][PF6]與[Emim][BF4]作為電致變色電解質層之效果，發現[Bmim][PF6]為本實驗架構下較適合之離子液，但仍存在褪色慢、褪色不完全的缺陷，因此進一步以UV固化電解質開發具備較好性能之電致變色元件，其在638.8 nm處穿透率可從8.88%變化至69.12%，並展現良好的切換速度和記憶效應。透過摻雜AG1、AZO1、S-428等二色性染料於液晶並結合本研究電致變色元件，驗證了液晶與電致變色技術結合的可行性，並實現不同的調光調色功能，其中液晶摻雜S-428結合電致變色元件於400 nm至800 nm波段範圍整體穿透率低至2.93%，展現最佳之暗態，因其具備高動態範圍與可視性佳等優點，未來可應用於AR/VR等穿戴式裝置之開發。;In general, liquid crystal technology often utilizes dye doping and Bragg reflection bandwidth to manage light absorption or color change. However, research on combining liquid crystals with an electrochromic layer to achieve dimming and color modulation is relatively scarce. Therefore, this study mainly explores the combination of an electrochromic layer with liquid crystal technology to create a novel display technology that incorporates the advantages of both. Firstly, this study attempted to use positive liquid crystal E7 doped with ion salt LiClO_4 to provide ions for the redox reactions in electrochromism, creating a liquid crystal electrochromic device by combining it with an electrochromic layer. However, it was found that the spontaneous vertical alignment of ions caused the liquid crystal to lose its birefringence. To address this issue, the study replaced the positive liquid crystal with negative liquid crystal HNG30400-200 and doped it with chiral dopants S811 to form a helical structure, enhancing ion migration. This device exhibited four operating states: colorless transparent, colored transparent, colored scattering, and colorless scattering. However, issues such as high operating voltage and unsatisfactory color uniformity persisted. The study then focused on improving electrochromic performance by comparing the effects of three ionic liquids: [Bmim][NTf2], [Bmim][PF6], and [Emim][BF4], as electrochromic electrolyte layers. It was found that [Bmim][PF6] was more suitable within the framework of this study, yet it still exhibited a slow and incomplete bleached state. Therefore, UV-curable electrolytes were used to create electrochromic devices with better performance, showing a transmittance change from 8.88% to 69.12% at 638.8 nm and demonstrating good switching speed and memory effect. By doping dichroic dyes AG1, AZO1, and S-428 into the liquid crystal and combining them with the electrochromic devices developed in this study, the feasibility of combining liquid crystal and electrochromic layers was verified, achieving dimming and color modulation. Among them, the device of liquid crystal doped with S-428 combined with the electrochromic layer showed the best dark state with an overall transmittance as low as 2.93% across the wavelength band between 400 nm and 800 nm. Due to its high dynamic range and good visibility, it has potential applications in the development of wearable devices such as AR/VR.
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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