Fluorescence quenching in an organic donor-acceptor dyad: a first principles study

Area of Science:

• Organic electronics
• Photophysics
• Computational chemistry

Background:

• Perylene bisimide (PBI) and triphenyl diamine (TPD) are key organic dyes in solar cells and light-emitting devices.
• Förster resonance energy transfer (FRET) experiments showed unexpected fluorescence quenching in a bridged PBI-TPD system.

Purpose of the Study:

• Investigate the cause of fluorescence quenching in a bridged PBI-TPD dyad.
• Elucidate the role of the saturated alkyl bridge in this phenomenon.

Main Methods:

• Time-dependent density functional theory (TD-DFT) calculations.
• Molecular dynamics (MD) simulations.

Main Results:

• Conformational dynamics of the bridged system were analyzed.
• A charge transfer process between the donor (TPD) and acceptor (PBI) was identified as the cause of quenching.

Conclusions:

• The saturated bridge's conformational dynamics induce inter-dye charge transfer, leading to fluorescence quenching.
• This finding is vital for designing efficient organic electronic devices by controlling intramolecular interactions.