Abstract
Luminescent solar concentrator (LSC) is a promising technology to integrate semitransparent photovoltaic (PV) systems into modern buildings and vehicles. Silicon quantum dots (QDs) are good candidates as fluorophores in LSCs, due to the absence of overlap between absorption and emission spectra, high photoluminescence quantum yield (PLQY), good stability, nontoxicity, and element abundance. Herein, LSCs based on Si QDs/polymer nanocomposites are fabricated in a triplex glass configuration. A special polymer matrix (off‐stoichiometric thiol‐ene, OSTE) is used, which improves Si nanocrystal quantum yield. Herein, a comprehensive investigation to improve the performance of LSCs by exploring different strategies under the guidance of a theoretical description is conducted. Among these strategies, the systematical enhancement of PLQY of the nanocomposite is achieved by tuning the thiol/allyl group ratio in the OSTE matrix. In addition, ligand selection and loading optimization for QDs reduce the total scattering loss in the device. Finally, an optical power efficiency of 7.9% is achieved for an optimized LSC prototype (9 × 9 × 0.6 cm3, transmittance ≈62% at 500 nm) based on Si QDs/OSTE nanocomposite, which shows good potential of this material system in LSC fabrication.
Highlights
The Transmission electron microscope (TEM) image of the as-synthesized Si quantum dots (QDs) (Figure S2, Supporting Information) revealed an average particle size of 5–7 nm, which is consistent with other works.[8a,15] Due to the indirect band-gap nature of Si QDs, a large Stokes shift was observed (Figure S3, Supporting Information), which fulfils the fundamental requirement of fluorophores in Luminescent solar concentrators (LSCs)
To fabricate the LSCs based on Si QDs/off-stoichiometric thiol-ene (OSTE) nanocomposite, the purified Si QDs were thoroughly mixed with thiol and allyl monomers, as well as a photoinitiator, to form a stable and transparent solution, which was slowly poured in between two glass sheets
Triplex-structured LSCs based on Si QDs/OSTE nanocomposites were demonstrated
Summary
Si QDs were synthesized from a commercial precursor, hydrogen silsequioxane (HSQ), by following a reported method.[14]. The annealed HSQ was etched by the HF solution to release Si QDs from the matrix. After HF etching, the obtained hydride-terminated Si QDs were transferred to an argon-filled Schlenk line and functionalized by methyl 10-undecenoate, for fabricating ester-capped QDs. The TEM image of the as-synthesized Si QDs (Figure S2, Supporting Information) revealed an average particle size of 5–7 nm, which is consistent with other works.[8a,15] Due to the indirect band-gap nature of Si QDs, a large Stokes shift was observed (Figure S3, Supporting Information), which fulfils the fundamental requirement of fluorophores in LSCs. To fabricate the LSCs based on Si QDs/OSTE nanocomposite, the purified Si QDs were thoroughly mixed with thiol and allyl monomers, as well as a photoinitiator, to form a stable and transparent solution, which was slowly poured in between two glass sheets. Polymerization was initiated by UV irradiation to prepare triplex glass units
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