In Situ Transformation of Electrum Nanoclusters Embedded in Polymer Matrices Exhibit Near‐Infrared Emission With Quantum Yield Exceeding 70%

Abstract A nanocomposite of metal nanoclusters/OSTE is fabricated through off‐stoichiometric thiol‐ene polymerization, incorporating adamantanethiol‐protected electrum nanoclusters Au_23‐xAg_x(SAdm)₁₅ (where x = 7.44) along with the OSTE monomer. During the photopolymerization, there is a transforfation of the precursor nanoclusters and the nanocomposite achieves a maximum photoluminescence quantum yield of ≈73% at 740 nm and 60% at the 850 nm emission peak. The photophysical characteristics of nanocomposite AuAgNCs@OSTE are examined at both ambient and low temperatures, revealing an improved radiative recombination mechanism through the interactions with polymer radicals. This high photoluminescence quantum yield near‐infrared‐emitting AuAgNCs@OSTE material, distinguished by a larger Stokes shift, is utilized to fabricate luminescent solar concentrators measuring 5 × 5 × 0.13 cm³. Experimental measurements are conducted to determine the absorption coefficient, reabsorption coefficient, absorption cross‐section, and volume concentration of the device. Additionally, theoretical evaluations of waveguiding efficiency and power conversion efficiency are performed and compared with quantum dot‐based alternatives. The findings indicate that the metal NCs@OSTE nanocomposite has the potential to function as a highly efficient, heavy‐metal‐free nanophosphor, demonstrating superior overall performance for semi‐transparent luminescent solar concentrator devices and being suitable for a broad range of light conversion applications in the NIR spectrum.