Electrochromic Switch Devices Mixing Small- and Large-Sized Upconverting Nanocrystals

authors	Martinez, ED; Brites, CDS; Carlos, LD; Garcia-Flores, AF; Urbano, RR; Rettori, C
nationality	International
journal	ADVANCED FUNCTIONAL MATERIALS
author keywords	electrothermal control; high thermal sensitivity; optoelectronic devices; silver nanowires; upconversion nanoparticles
keywords	UP-CONVERSION LUMINESCENCE; TEMPERATURE-DEPENDENCE; NANOWIRE NETWORKS; NANOPARTICLES; SHELL; CORE; ER3+; PHASE; STATE
abstract	The hasty progress in smart, portable, flexible, and transparent integrated electronics and optoelectronics is currently one of the driving forces in nanoscience and nanotechnology. A promising approach is the combination of transparent conducting electrode materials (e.g., silver nanowires, AgNWs) and upconverting nanoparticles (UCNPs). Here, electrochromic devices based on transparent nanocomposite films of poly(methyl methacrylate) and AgNWs covered by UCNPs of different sizes and compositions are developed. By combining the electrical control of the heat dissipation in AgNW networks with size-dependent thermal properties of UCNPs, tunable electrochromic transparent devices covering a broad range of the chromatic diagrams are fabricated. As illustrative examples, devices mixing large-sized (>70 nm) beta-NaYF4:Yb,Ln and small-sized (<15 nm) NaGdF4:Yb,Ln@NaYF4 core@shell UCNPs (Ln = Tm, Er, Ce/Ho) are presented, permitting to monitor the temperature-dependent emission of the particles by the intensity ratio of the Er3+ 2H11/2 and S-4(3/2) -> I-4(15/2) emission lines, while externally controlling the current flow in the AgNW network. Moreover, by defining a new thermometric parameter involving the intensity ratio of transitions of large- and small-sized UCNPs, a relative thermal sensitivity of 5.88% K-1 (at 339 K) is obtained, a sixfold improvement over the values reported so far.
publisher	WILEY-V C H VERLAG GMBH
issn	1616-301X
isbn	1616-3028
year published	2019
volume	29
issue	8
digital object identifier (doi)	10.1002/adfm.201807758
web of science category	Chemistry, Multidisciplinary; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter
subject category	Chemistry; Science & Technology - Other Topics; Materials Science; Physics
unique article identifier	WOS:000459826500020