Electrochromic devices (ECDs) are emerging as novel technology for various applications ranging from commercialized smart window glasses, goggles, and autodimming rear view mirrors to uncommon yet more sophisticated applications such as infrared camouflage in military and thermal control in space satellites. The development of low-power, lightweight, inexpensive, and flexible devices is the need of the hour. In this respect, utilizing PEDOT:PSS as transparent conducting electrode (TCE) to replace indium tin oxide (ITO) and metal based TCEs for ECDs is a promising solution for the aforementioned requirements. In this work we have demonstrated the performance of PEDOT:PSS films coated on flexible substrates, treated with PTSA-DMSO, as TCEs for ECD applications and their comparison with that of ITO based ECDs. The PEDOT:PSS based flexible TCEs used in this study have conductivity of 1400-1500 S·cm and figure of merit (FoM) of 70-77. The process of increasing the conductivity of PEDOT:PSS films also led to the broadening of the conducting potential window (CPW), which is important for electrochemical applications of PEDOT:PSS when used as a stand-alone electrode. More than achieving a comparable electrochromic contrast, switching time, and coloration efficiency with respect to the ITO based ECDs, PEDOT:PSS devices also had the added advantage of good mechanical flexibility. These devices demonstrated superior stability during electrochemical cycling and multiple mechanical bending tests, making them an inexpensive alternative to the costly ITO based ECD technology.

Hollow bimetallic nanostructures have recently emerged as attractive plasmonic materials due to the ease of optical tunability by changing their size/composition. Currently available methods, in addition to being tedious and time-consuming, result in polydispersed nanostructures, particularly due to polydispersed templates. In this study, optically tunable hollow gold nanostructures (HGNS) were synthesized by 10 galvanic replacement reaction between silver nanospheres (AgNS) templates and gold salt. Monodispersed AgNS were created using a gold seed-mediated heteroepitaxial growth. Since it is easier to ensure monodispersed gold nanosphere seeds, the resulting AgNS showed a tight control on size. Hollow gold nanostructures 43 -70 nm in size with extinction maxima ranging between 450 -590 nm were produced by varying the gold to silver molar ratio. The nanostructures were observed to be 15 monodispersed and uniform (SD ≤11%) in all the batches. Furthermore, the synthesized HGNS were immobilized on dendrimer-functionalized U-shaped fiber-optic probes to develop a localized surface plasmon resonance (LSPR) based sensor. Refractive index sensitivity of the HGNS based sensors was found to be 1.5-fold higher than solid gold nanosphere (GNS)-based fiber-optic sensors. These HGNSbased fiber-optic probes were subsequently used to develop an immunosensor with improved sensitivity 20 by using human immunoglobulin-G (HIgG) as receptor molecules and goat-anti-HIgG as a target analyte. 22 2572 3480; Tel: +91 22 2576 776 90 † Electronic Supplementary Information (ESI) available: Method of gold seed particle synthesis; Extinction spectrum and FEG-TEM image of gold seed particles; chemical reactions involved in the preparation diamine silver complex; Extinction spectra, FEG-TEM image and histogram of silver nanoparticles produced from heteroepitaxial growth method using 95

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In this paper, we report a novel, eco-friendly method for the preparation of gold nanoshells (GNS) with unprecedented colloidal stability. Gold shell layers were grown on silica nanospheres by utilizing glucose. Nanoshell morphology was optimized by varying the molar ratio of glucose to gold, and was characterized using UV-vis spectroscopy and transmission electron microscopy (TEM). The colloidal stability of the prepared nanoshells was compared to those made using formaldehyde reductant, using sequential extinction intensity measurements and electron microscopy. Fourier transform infrared spectroscopy was used to elucidate their surface chemistry. Uniformity and homogeneity in the shells was achieved at a molar ratio of 2, followed by shell thinning at higher glucose concentrations. These colloids exhibited remarkable stability, compared to those prepared with the commonly reported protocol, where formaldehyde is employed as the reducing agent. The key role played by glucose in imparting high stability, in conjunction with its reducing properties is demonstrated. Furthermore, the sensing potential of these nanoshells was demonstrated using surface enhanced Raman scattering (SERS) in the near-infrared region on an optical fiber platform. The present approach offers an ecofriendly route for the production of nanoshells with high stability, augmenting their use for sensing and in vivo applications, where highly stable and unaggregated nanoshells are preferred. By eliminating the routinely used noxious formaldehyde, this method presents itself as a safe, scalable and direct route for the synthesis of glucose capped nanoshells, which are much sought after for therapeutic applications.

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