Browsing by Author "Chen, Chih Hao"

Now showing 1 - 2 of 2

Fabrication of Flexible Electrochromic Devices Based on Tungsten Trioxide Nanobundles
(2016)
Chen, Chih Hao
;
Tseng, Tseung-Yuen
;
Hung, Chung Jung
;
材料科學與工程學系
;
電子工程學系及電子研究所
Low-cost and facile approach to grow quasi-one-dimensional hexagonal tungsten trioxide nanobundles(Q1D hex-W0(3) NBs) on indium tin oxide (ITO) coated flexible polyethylene terephthalate (PET) substrate via hydrothermal method combined with electrophoretic deposition (EPD) technique is reported. Influence of the precursor concentration and hydrothermal reaction time on the morphology and size of as synthesized W0(3) nanostructures are investigated. Well-designed nanostructure exhibits remarkable enhancement in the electrochromic (EC) properties. In particular, a significant optical modulation (44% at 700 nm), fast color switching speed (bleaching: 22 s and coloration: 9 s), high coloration efficiency (89.8 cm(2) C-1 at 700 nm), high Li+ diffusion coefficient (8.92 x 10(-10) cm(2) s(-1)), and excellent cycling stability (74% after 1000 cycles) are achieved for the QM hex-W0(3) Nils film. Improved EC properties are mainly attributed from the Q1D hex-W0(3) NBs. Li+ can transport quickly and easily diffused into the storage sites of the interface of the Nils. Furthermore, we also reported a large areal flexible EC device (70 mm x 70 mm) with a simple two electrode configuration exhibiting outstanding mechanical flexibility and high optical contrast. The QM hex-WO3 NBs film acts as an excellent EC material.
Hydrothermal Formation of Tungsten Trioxide Nanowire Networks on Seed-Free Substrates and Their Properties in Electrochromic Device
(2014-05-01)
Hung, Chung Jung
;
Huang, Yi Hsuan
;
Chen, Chih Hao
;
Lin, Pang
;
Tseng, Tseung Yuen
Facile and cost-efficient hydrothermally grown 3-D tungsten trioxide (WO3) nanowires (NWs) network film on seed-free fluorine-doped tin oxide (FTO) substrates without using additive or capping agent is reported. The NW networks are hexagonal phase and the morphologies are changed by adjusting the pH of precursor solutions. Growth mechanism of WO3 NWs is also extensively discussed. The designed porous film exhibits remarkable enhancement of the electrochromic (EC) properties. In particular, a significant optical modulation (57% at 632 nm), fast color switching speed (bleaching: 7 s and coloration: 21 s), high coloration efficiency (120.3 cm(2) C-1 at 632 nm), high Li+ diffusion coefficient (2.14 x 10(-9) cm(2) s(-1)), and excellent cycling stability (87% after 1000 cycles) are achieved for the 3-D NWs film. The improved EC properties are mainly attributed to the highly porous film, which makes the Li+ diffusion becomes easier and provides larger specific surface area for charge-transfer reactions. Furthermore, we also reported an EC device (50 mm x 50 mm) with a simple two-electrode configuration showing high optical contrast. The 3-D WO3 NWs network film acts as an excellent EC material.