Coumarin dyes for dye-sensitized solar cells: A long-range-corrected density functional study

Area of Science:

• Computational Chemistry
• Materials Science
• Photovoltaics

Background:

• Solar cell dyes require accurate excited-state property calculations.
• Traditional functionals like B3LYP show limitations for larger molecules.
• Long-range-corrected (LC) functionals offer a potential improvement.

Purpose of the Study:

• Investigate excited-state properties of coumarin solar cell dyes.
• Assess the performance of LC functionals with varying range-separation parameters (μ).
• Compare LC-TDDFT results with coupled-cluster calculations.

Main Methods:

• Time-dependent density functional theory (TDDFT) with LC functionals.
• Calculation of excitation energies, oscillator strengths, and dipole moments.
• Comparison with approximate coupled-cluster singles and doubles (CCSD(T)) results.

Main Results:

• Optimized LC functionals provide consistent charge-transfer excitation descriptions.
• B3LYP functional overestimates excited-state dipole moments and underestimates excitation energies.
• LC-TDDFT shows improved accuracy for larger coumarin dye molecules.

Conclusions:

• Long-range exchange corrections are crucial for accurate TDDFT in solar cell dyes.
• LC functionals offer a more reliable approach for predicting dye performance.
• Properly chosen LC functionals enhance the understanding of electronic processes in organic photovoltaics.