Electronic properties of indan-1,3-dione-carbazole-based compounds revealed by time resolved spectroscopy

• New donor-acceptor materials were synthesized.
• IDC chromophores weakly interact in quadruplicate molecules in solutions.
• IDC chromophores experience ultrafast excited state relaxation.
• Quadruplicate molecules form no aggregate states in solid films.
• Potential applications as saturable absorbers.

Two new indan-1,3-dione and carbazole-based (IDC) compounds with single and four covalently connected chromophores were synthesized and their optical properties were investigated in solutions and in solid films with the emphasis on the interchromophore interactions. Because of molecule twisting, opening transitions to nπ* states, IDC chromophores experience ultrafast excited state relaxation with the time constant of about 2 ps in solutions and several times slower solid films. Chromophore connection into quadruplicate molecules only weakly influence their spectroscopic properties in solutions, however prevents H-type aggregate formation and concomitant spectral changes in solid films.

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