Li(+)- and Eu(³+)-doped poly(ε-caprolactone)/siloxane biohybrid electrolytes for electrochromic devices

Luminescent Electrochromic Devices for Smart Windows of Energy-Efficient Buildings

To address the challenges of the next generation of smart windows for energy-efficient buildings, new electrochromic devices (ECDs) are introduced. These include indium molybdenum oxide (IMO), a conducting oxide transparent in the near-infrared (NIR) region, and a NIR-emitting electrolyte. The novel electrolytes are based on a sol-gel-derived di-urethane cross-linked siloxane-based host structure, including short chains of poly (ε-caprolactone) (PCL(530) (where 530 represents the average molecular weight in g mol−1). This hybrid framework was doped with a combination of either, lithium triflate (LiTrif) and erbium triflate (ErTrif3), or LiTrif and bisaquatris (thenoyltrifluoroacetonate) erbium (III) ([Er(tta)3(H2O)2]). The ECD@LiTrif-[Er(tta)3(H2O)2] device presents a typical Er3+ NIR emission around 1550 nm. The figures of merit of these devices are high cycling stability, good reversibility, and unusually high coloration efficiency (CE = ΔOD/ΔQ, where Q is the inserted/de-inserted charge density). CE values of −8824/+6569 cm2 C−1 and −8243/+5200 cm2 C−1 were achieved at 555 nm on the 400th cycle, for ECD@LiTrif-ErTrif3 and ECD@LiTrif-[Er(tta)3(H2O)2], respectively.

The molecular basis of memory

We propose a tripartite biochemical mechanism for memory. Three physiologic components are involved, namely, the neuron (individual and circuit), the surrounding neural extracellular matrix, and the various trace metals distributed within the matrix. The binding of a metal cation affects a corresponding nanostructure (shrinking, twisting, expansion) and dielectric sensibility of the chelating node (address) within the matrix lattice, sensed by the neuron. The neural extracellular matrix serves as an electro-elastic lattice, wherein neurons manipulate multiple trace metals (n > 10) to encode, store, and decode coginive information. The proposed mechanism explains brains low energy requirements and high rates of storage capacity described in multiples of Avogadro number (N(A) = 6 × 10(23)). Supportive evidence correlates memory loss to trace metal toxicity or deficiency, or breakdown in the delivery/transport of metals to the matrix, or its degradation. Inherited diseases revolving around dysfunctional trace metal metabolism and memory dysfunction, include Alzheimer's disease (Al, Zn, Fe), Wilson's disease (Cu), thalassemia (Fe), and autism (metallothionein). The tripartite mechanism points to the electro-elastic interactions of neurons with trace metals distributed within the neural extracellular matrix, as the molecular underpinning of "synaptic plasticity" affecting short-term memory, long-term memory, and forgetting.

Hybrid materials and polymer electrolytes for electrochromic device applications

Electrochromic (EC) materials and polymer electrolytes are the most imperative and active components in an electrochromic device (ECD). EC materials are able to reversibly change their light absorption properties in a certain wavelength range via redox reactions stimulated by low direct current (dc) potentials of the order of a fraction of volts to a few volts. The redox switching may result in a change in color of the EC materials owing to the generation of new or changes in absorption band in visible region, infrared or even microwave region. In ECDs the electrochromic layers need to be incorporated with supportive components such as electrical contacts and ion conducting electrolytes. The electrolytes play an indispensable role as the prime ionic conduction medium between the electrodes of the EC materials. The expected applications of the electrochromism in numerous fields such as reflective-type display and smart windows/mirrors make these materials of prime importance. In this article we have reviewed several examples from our research work as well as from other researchers' work, describing the recent advancements on the materials that exhibit visible electrochromism and polymer electrolytes for electrochromic devices. The first part of the review is centered on nanostructured inorganic and conjugated polymer-based organic-inorganic hybrid EC materials. The emphasis has been to correlate the structures, morphologies and interfacial interactions of the EC materials to their electronic and ionic properties that influence the EC properties with unique advantages. The second part illustrates the perspectives of polymer electrolytes in electrochromic applications with emphasis on poly (ethylene oxide) (PEO), poly (methyl methacrylate) (PMMA) and polyvinylidene difluoride (PVDF) based polymer electrolytes. The requirements and approaches to optimize the formulation of electrolytes for feasible electrochromic devices have been delineated.