Solar spectral management with electrochromic devices including PMMA films doped with biluminescent ionosilicas

Abstract

The technological potential of poly(methyl methacrylate) (PMMA)-based composite films doped with lanthanide-doped sol-gel derived ionosilicas (IS-Ln) previously proposed for luminescent down-shifting (LDS) and luminescent solar concentrator (LSC) layers connected to photovoltaic (PV) cells is extended here to electrochromic devices (ECDs), targeting the fabrication of single energy harvesting/conversion/management LSC-LDS/PV/ECD systems. These integrated devices have foreseen application in the windows of future zero-energy buildings of smart cities. The proof-of-concept is given with the report of the electro-optical performance of an ECD comprising an optimized electrolyte film composed of PMMA, IS-Nd, and IS-Eu, and the 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid. This amorphous electrolyte is stable below 160 degrees C, exhibits high ionic conductivity (2.13 x 10(-4) and 8.76 x 10(-4) S cm(-1) at room temperature and 44 degrees C, respectively), and emits in the visible (red color) and near-infrared (NIR) spectral regions. The device demonstrated fast switching speed (50 s) and high transparency in the visible-to-NIR spectral regions (transmittance (T) = 79/96/89/77% at 555/1000/1500/1650 nm in the as-prepared state, respectively). Upon application of +/- 2.5 V for 200 cycles, at the same wavelengths, the T-bleached/T-colored values were 44/28, 46/26, 39/20, and 27/9%, respectively, and the coloration efficiency (CE) values CEin/CEout values were -302/+181, -381/+228, -446/+267 and -734/+440 cm(2) C-1, respectively.