Luminescent solar concentrators (LSCs) appear as candidates to enhance the performance of photovoltaic (PV) cells and contribute to reduce the size of PV systems, decreasing, therefore, the amount of material needed and thus the cost associated with energy conversion. One way to maximize the device performance is to explore near-infrared (NIR)-emitting centers, resonant with the maximum optical response of the most common Si-based PV cells. Nevertheless, very few examples in the literature demonstrate the feasibility of fabricating LSCs emitting in the NIR region. In this work, NIR-emitting LSCs are reported using silicon 2,3-naphthalocyanine bis(trihexylsilyloxide) (SiNc or NIR775) immobilized in an organic-inorganic tri-ureasil matrix (t-U(5000)). The photophysical properties of the SiNc dye incorporated into the tri-ureasil host closely resembled those of SiNc in tetrahydrofuran solution (an absolute emission quantum yield of ∼0.17 and a fluorescence lifetime of ∼3.6 ns). The LSC coupled to a Si-based PV device revealed an optical conversion efficiency of ∼1.5%, which is among the largest values known in the literature for NIR-emitting LSCs. The LSCs were posteriorly coupled to a Si-based commercial PV cell, and the synergy between the t-U(5000) and SiNc molecules enabled an effective increase in the external quantum efficiency of PV cells, exceeding 20% in the SiNc absorption region.

Development of natural-based luminescent solar concentrators able to convert sunlight into specific wavelengths which are guided by total internal reflection to a PV device featuring reliable, sustainable and competitive energy systems.

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.

pushed the efficiency of crystalline silicon (c-Si) PV cells to values approaching the theoretical limit of ≈33%. [3,4] One way to increase the efficiency of PV cells beyond this limit is through the use of luminescent solar concentrators (LSCs) that are devices comprising a transparent matrix embedding optically active centers that absorb the incident radiation, which is re-emitted at a specific wavelength and transferred by total internal reflection to PV cells located at the edges of the matrix. [5,6] Major advances on the LSCs' research can be found in recent reviews. [7][8][9][10][11][12][13] Nowadays, c-Si PV cells are the leader technology in the PV market presenting the higher performance in the nearinfrared (NIR) spectral region (from about 700 to 1100 nm), and, thus, NIR-emitting LSCs resonant with the maximum optical response of c-Si PV cells are looked for to maximize the device performance. Several examples pointed out the potential of NIR-emitting quantum dots (QDs), [14][15][16][17][18] but experimental results demonstrating its use in LSCs can only be found in a few reports. [2,[19][20][21][22][23][24] The maximum reported optical conversion efficiency (η opt ) value is 12.6%, considering all the edges of a planar LSC with PbS QDs. [20] Hexanuclear metal halide clusters [22] and a cyanine derivative [23] with emission in the NIR spectral range were also demonstrated to be suitable for LSCs, although no η opt values were presented. Very recently, some of us reported Luminescent solar concentrators (LSCs) appear as an intriguing way to cope with the limitation of the mismatch between the photovoltaic (PV) cells response and the solar spectrum, with the additional advantage of facilitating urban integration of photovoltaics. A new LSCs geometry based on triangular hollow-core plastic optical fibers (POFs) filled with organic-inorganic hybrid materials doped with Rhodamine 6G, Rhodamine 800, or an Europiumβ-diketonate complex is presented. Large-area LSCs are built from POFs bundle structures, whose assembling is favored by the fiber triangular cross section that also maximizes the coverage of a PV cell surface compared with cylindrical POFs. Each bundle fiber behaves as an individual LSC absorbing UV/blue components of the solar spectrum and emitting visible/NIR radiation. The LSCs are characterized by optical conversion efficiency values up to η opt ≈5.3%, among the largest values reported for single-layer LSCs. Moreover, the coupling between the LSCs to commercial Si PV cells yields maximum power conversion efficiency values of PCE ≈0.74%. The individual waveguiding features of each fiber in the bundle contribute to reduce the reabsorption, as lower performance values (η opt ≈1.5%; PCE ≈0.09%) are estimated for a planar LSC with analogous surface collection area and lightharvesting absorbance.