Unraveling the Photovoltaic Potential of a Novel Fluorescent Quinoline Heterocycle: Synthesis, Spectroscopic, Photophysical and DFT Studies for High-Efficiency DSSCs.

Authors

Donya Jaroubi Eftekhari, Mehdi Pordel, Ali Javid, S Ali Beyramabadi

Published in

Journal of fluorescence. Jun 24, 2026. Epub Jun 24, 2026.

Abstract

Dye-sensitized solar cells (DSSCs) are a promising class of photovoltaic devices owing to their low-cost fabrication and tunable optoelectronic properties. In this study, a novel quinoline-based fluorescent heterocyclic dye was designed and synthesized by incorporating electron-rich heterocycles and a cyano group to promote intramolecular charge transfer (ICT). The target compound was obtained in 62% yield and fully characterized using spectroscopic techniques (¹H NMR, ¹³C NMR, FT-IR, MS, and elemental analysis). The dye exhibits strong visible absorption (λ_abs = 405 nm), high molar extinction coefficient (ε = 89,000 M^- 1 cm^- 1), and significant fluorescence emission (λ_em = 495 nm) with a quantum yield of Φ_F = 0.69 in methanol. Electrochemical studies revealed a reversible oxidation process, allowing the estimation of the HOMO (- 4.47 eV) and LUMO (- 1.58 eV) energy levels, which are compatible with electron injection into TiO₂. When applied as a sensitizer in DSSCs, the dye delivered a power conversion efficiency (PCE) of 5.50 ± 0.18%, with J_sc = 13.9 ± 0.25 mA cm^- 2, V_oc = 0.55 ± 0.01 V, and FF = 72 ± 1.5, under AM 1.5G illumination. Electrochemical impedance spectroscopy indicated efficient charge transport and reduced charge recombination. Density functional theory (DFT) calculations supported the experimental findings, confirming the spatial separation of frontier orbitals and the ICT character. Moreover, TD-DFT studies showed excellent agreement with the experimental absorption data and confirmed the strong ICT nature of the electronic transitions in dye 5. These results suggest that quinoline-based heterocyclic systems are promising building blocks for the development of organic sensitizers for DSSC applications.

PMID:
42340567
Bibliographic data and abstract were imported from PubMed on 24 Jun 2026.

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