Luminescent nanomaterials have shown promise for thermal sensing in bio‐applications, yet little is known of the role of organic coatings such as supported lipid bilayers on the thermal conductivity between the nanomaterial and its environment. Additionally, since the supported lipid bilayer mimics the cell membrane, its thermal properties are fundamentally important to understand the spatial variations of temperature and heat transfer across membranes. Herein, a new approach is described that enables direct measurement of these thermal properties using a LiYF₄:Er³⁺/Yb³⁺ upconverting nanoparticle encapsulated within a conformal supported lipid bilayer and dispersed in water as a temperature probe yielding the temperature gradient across the bilayer. The thermal conductivity of the lipid bilayer is measured as a function of the temperature, being 0.20 ± 0.02 W m⁻¹ K⁻¹ at 300 K. For the uncapped nanoparticles dispersed in water, the temperature dependence of the thermal conductivity is also measured in the 300–314 K range as [0.63–0.69] ± 0.11 W m⁻¹ K⁻¹. Using a lumped elements model, the directional heat transfer is calculated at each of the system interfaces, namely, nanoparticle–bilayer and bilayer–nanofluid, opening a new avenue to understand the membrane biophysical properties as well as the thermal properties of organic and polymer coatings.

The integration of photovoltaic (PV) elements in urban environments is gaining visibility due to the current interest in developing energetically self-sustainable buildings. Luminescent solar concentrators (LSCs) may be seen as a solution to convert urban elements, such as façades and windows, into energy-generation units for zero-energy buildings. Moreover, LSCs are able to reduce the mismatch between the AM1.5G spectrum and the PV cells absorption. In this work, we report optically active coatings for LSCs based on lanthanide ions (Ln³⁺ = Eu³⁺, Tb³⁺)-doped surface functionalized ionosilicas (ISs) embedded in poly(methyl methacrylate) (PMMA). These new visible-emitting films exhibit large Stokes-shift, enabling the production of transparent coatings with negligible self-absorption and large molar extinction coefficient and brightness values (~2 × 10⁵ and ~10⁴ M⁻¹∙cm⁻¹, respectively) analogous to that of orange/red-emitting organic dyes. LSCs showed great potential for efficient and environmentally resistant devices, with optical conversion efficiency values of ~0.27% and ~0.34%, respectively.

Luminescent solar concentrators (LSCs) are luminescent waveguide layers that convert sunlight into specific wavelengths which are then guided by total internal reflection to a PV device located at the edges of the LSC. Their ability to concentrate sunlight onto small areas makes LSCs a useful complement to silicon-based PVs in a series of applications, such as urban integration and flexible fabrics towards mobile solar-energy. Challenges for the luminescent layer include the use of low-cost and sustainable nature-based organic molecules. We report novel chlorophyll-based LSCs with emission properties in the red/NIR spectral region. Here, chlorophyll molecules extracted from Spirulina maxima, an abundant cyanobacterium and an attractive natural source, are immobilized in organic–inorganic di- and tri-ureasil matrices enabling the production of sustainable LSCs. At low chlorophyll concentrations (<3 × 10¹⁷ molecules per cm³), the photophysical properties of the chlorophyll molecules after incorporation into the hybrids closely resemble those in ethanolic solution (with an absolute emission quantum yield of ∼0.16 and a fluorescence lifetime of ∼8 ns). The LSCs were coupled to a Si-based commercial PV device revealing optical conversion efficiency and power conversion efficiency values of ∼3.70% and 0.10%, respectively, illustrating the potential of this approach for the development of nature-based LSCs meeting the requirements of reliable, sustainable and competitive energy systems.

The development of portable low-cost integrated optics-based biosensors for photonics-on-a-chip devices for real-time diagnosis are of great interest, offering significant advantages over current analytical methods. We report the fabrication and characterization of an optical sensor based on a Mach-Zehnder interferometer to monitor the growing concentration of bacteria in a liquid medium. The device pattern was imprinted on transparent self-patternable organic-inorganic di-ureasil hybrid films by direct UV-laser, reducing the complexity and cost production compared with lithographic techniques or three-dimensional (3D) patterning using femtosecond lasers. The sensor performance was evaluated using, as an illustrative example, E. coli cell growth in an aqueous medium. The measured sensitivity (2 × 10⁻⁴ RIU) and limit of detection (LOD = 2 × 10⁻⁴) are among the best values known for low-refractive index contrast sensors. Furthermore, the di-ureasil hybrid used to produce this biosensor has additional advantages, such as mechanical flexibility, thermal stability, and low insertion losses due to fiber-device refractive index mismatch (~1.49). Therefore, the proposed sensor constitutes a direct, compact, fast, and cost-effective solution for monitoring the concentration of lived-cells.

The mismatch between the AM1.5G spectrum and the photovoltaic (PV) cells absorption is one of the most limiting factors for PV performance. To overcome this constraint through the enhancement of solar energy harvesting, luminescent downshifting (LDS) layers are very promising to shape the incident sunlight and, thus, we report here the use of Tb3+- and Eu3+-doped organic-inorganic hybrid materials as LDS layers on Si PV cells. Electrical measurements on the PV cell, done before and after the deposition of the LDS layers, confirm the positive effect of the coatings on the cell’s performance in the UV spectral region. The maximum delivered power and the maximum absolute external quantum efficiency increased 14% and 27%, respectively. Moreover, a solar powered car race was organized in which the small vehicle containing the coated PV cells presented a relative increase of 9% in the velocity, when compared to that with the uncoated one.