Bilayer Thin Films That Combine Luminescent and Spin Crossover Properties for an Efficient and Reversible Fluorescence Switching

Abstract

We report on the vacuum thermal deposition of bilayer thin films of the luminescent complex Ir(ppy)3, tris[2-phenylpyridinato-C2,N]iridium(III), and the spin crossover complex [Fe(HB(tz)3)2], bis[hydrotris(1,2,4-triazol-1-yl)borate]iron(II). Switching the spin state of iron ions from the low spin to the high spin state around 337 K leads to a reversible jump of the luminescence intensity, while the spectrum shape and the luminescence lifetime remain unchanged. The luminescence modulation occurs due to the different UV light absorption properties of the iron complex in the two spin states and its magnitude can therefore be precisely adjusted by varying the film thickness. These multilayer luminescence switches hold potential for micro- and nanoscale thermal sensing and imaging applications.

Synergic Bistability between Spin Transition and Fluorescence in Polyfluorene Composites with Spin Crossover Polymers

“…As stated above, the synergy between the spin crossover and fluorescence has been explained in two different ways. (i) The luminescence of the fluorophore can be re-absorbed by the SC compound, 14,18,24 or (ii) environmental effects derived from the spin transition-induced lattice changes can affect the luminescence of the fluorophore. 15,20 In our case, the different experimental evidence suggests that the synergy between the spin crossover and fluorescence observed in our composites can be assigned to environmental lattice changes due to the spin transition.…”

“…In the composite materials, the fluorescence intensity tends to increase at high temperatures upon the spin transition into the HS state, which has been assigned to either (i) bleaching of the absorption band of the LS state, which would be partially quenching the fluorescence (either by absorption of the photons emitted by the fluorophore or by Forster-type nonradiative energy transfer), or (ii) lattice changes associated with the spin transition. The former was clearly evidenced in a bilayer film with a Ru complex, where the layer of the SC compound in LS acted as an optical filter, 24 whereas the later was proven in pyrene-grafted core−shell nanoparticles. 15 Pyrene can emit as a monomer or an excimer, and in this work, the authors observed that only the excimer emission was modulated by the spin transition.…”

Heat Capacity and Thermal Damping Properties of Spin‐Crossover Molecules: A New Look at an Old Topic

“…A 900 nm‐thick film of 1 was then deposited on top of the chip by vacuum thermal evaporation, as described recently. [ 21 ] It is important to mention that both the deposition conditions as well as the physical properties of the SCO film are not invasive and do not modify the electrical performance of the device. The SCO‐coated chip was then mounted on a variable temperature stage to control the temperature of the entire substrate.…”

Fabrication and characterizations of Cr3+‐doped ZnGa2O4 transparent ceramics with persistent luminescence

“…At present, long afterglow materials are mainly used in low‐light display, anti‐counterfeiting, and decoration in the form of phosphor powders. Predictably, Cr‐doped ZnGa 2 O 4 transparent ceramics with persistent luminescence certainly will have a wider range of applications 24–29 …”

“…Predictably, Cr-doped ZnGa 2 O 4 transparent ceramics with persistent luminescence certainly will have a wider range of applications. [24][25][26][27][28][29] In this work, the co-precipitation method was used to prepare Cr-doped ZnGa 2 O 4 nanopowders, and the pure phase ZnGa 2 O 4 powders were obtained by selecting the appropriate precipitator and adjusting its dosage. On this basis, the appropriate molding process and sintering strategy were innovatively used to prepare Cr-doped ZnGa 2 O 4 transparent ceramics with persistent luminescence.…”