روح الله غلامی

Blue-emissive nitrogen- and sulfur-doped carbon dots (CDs) were synthesized via a solvothermal route and subsequently employed as luminophores in luminescent solar concentrators (LSCs) fabricated with glass, PMMA, and reflux glass waveguides. The prepared CDs exhibited characteristic excitation-dependent PL, with a dominant PLE band centered at 405–410 nm. Under excitation at 400–410 nm, the CDs produced intense blue emission centered at 455–460 nm, while increasing the excitation wavelength from 330 to 500 nm resulted in a progressive red shift of the emission to approximately 560 nm, accompanied by spectral broadening (FWHM≈ 70–100 nm) and reduced emission intensity. The excellent optical characteristics of the CDs were reflected in the photovoltaic performance of the fabricated LSCs, where device efficiency depended strongly on fluorophore concentration and waveguide material. Increasing the CD loading from 1 to 3 wt.% significantly enhanced the short-circuit current and optical harvesting efficiency for all substrates, with the PMMA-based LSC achieving the best overall performance at 3 wt.% (Voc= 0.39 V, Isc= 3.52 mA, FF= 0.47, PCE = 0.054%, and ηopt= 1.64%), followed closely by the reflux glass device (PCE = 0.052%, ηopt= 1.62%). Further increasing the concentration to 5 wt.% reduced the photovoltaic performance owing to concentration-induced self-quenching, reabsorption, and scattering losses. Overall, the results demonstrate that a 3 wt.% CD loading in a PMMA waveguide provides the optimal balance between photon absorption, emission, and waveguiding efficiency, highlighting the potential of these blue-emissive CDs for high-performance LSCs and other photonic and optoelectronic applications.