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Updated: Jul 12, 2026

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation
Published on: October 10, 2018
Unveiling the Electronic and Optoelectronic Behavior of Phenothiazine Derivatives through Theoretical Insights
Murugesan Panneerselvam1,2, Anantha Narayanan Sri Gayathri3, Madhu Deepan Kumar4
1MolMod-CSInstituto de Química, Universidade Federal Fluminense, Campos Valonginho s/n, Centro, Niterói, Rio de Janeiro 24020-14, Brazil.
Abstract:
A series of phenothiazine-based donor-π-acceptor derivatives (PTZ1-PTZ10) were systematically designed and investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT) to elucidate structure-property relationships governing their optoelectronic performance. Strategic incorporation of aryl substituents with varying electronic character enables fine-tuning of molecular planarity, Frontier orbital energies and intramolecular charge transfer (ICT). Frontier molecular orbital analysis reveals efficient donor-acceptor separation across the series, with reduced band gaps and enhanced delocalization observed for PTZ6-PTZ10, promoting stronger ICT and improved light-harvesting capability. TD-DFT results indicate pronounced bathochromic shifts and high oscillator strengths for these derivatives, with absorption extending toward the visible region. Solvent-dependent studies further confirm strong solvatochromic behavior, highlighting the stabilization of charge-transfer excited states in polar environments. Excited-state analysis shows small singlet-triplet energy gaps (ΔE ST = 0.155-0.417 eV), suggesting efficient intersystem crossing and exciton utilization. Charge-transport analysis demonstrates that PTZ7 and PTZ10 are favorable for hole transport, while PTZ2 and PTZ5 exhibit superior electron-transport properties, with several derivatives displaying balanced ambipolar characteristics. Notably, PTZ10 exhibits the highest light-harvesting efficiency, favorable injection driving force and strong charge separation, identifying it as the most promising candidate for photovoltaic applications. Complementary NCI-RDG and QTAIM analyses reveal that hydrogen bonding and dispersion interactions play key roles in stabilizing molecular conformations and facilitating electronic communication. Overall, this study provides a comprehensive framework for the rational design of phenothiazine-based chromophores, offering valuable insights for the development of efficient materials for dye-sensitized solar cells and related optoelectronic devices.
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