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Electrochromic Switch Devices Mixing Small‐ and Large‐Sized Upconverting Nanocrystals
Author(s) -
Martínez Eduardo D.,
Brites Carlos D. S.,
Carlos Luís D.,
GarcíaFlores Alí F.,
Urbano Ricardo R.,
Rettori Carlos
Publication year - 2019
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201807758
Subject(s) - materials science , electrochromism , nanocomposite , optoelectronics , nanotechnology , nanocrystal , electrochromic devices , mixing (physics) , electrode , chemistry , physics , quantum mechanics
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) β‐NaYF 4 :Yb,Ln and small‐sized (<15 nm) NaGdF 4 :Yb,Ln@NaYF 4 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 Er 3+ 2 H 11/2 and 4 S 3/2 → 4 I 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.