Stepwise photoconversion of an artificial light-harvesting array built from extended BODIPY units

Area of Science:

• Photochemistry
• Materials Science
• Renewable Energy

Background:

• Artificial light-harvesting arrays require efficient energy transfer components.
• Boron dipyrromethene (BODIPY) dyes are explored for their photophysical properties.
• Organic solar cells benefit from novel sensitizing molecules.

Purpose of the Study:

• To investigate a molecular dyad composed of two BODIPY units as a component for artificial light-harvesting.
• To assess the efficiency of intramolecular electronic energy transfer and potential competing processes.
• To evaluate the stability and performance of the dyad in organic solar cells under illumination.

Main Methods:

• Synthesis and characterization of a molecular dyad with two extended BODIPY units.
• Photophysical studies including energy transfer efficiency, excited-state lifetime, and quantum yield measurements.
• Photochemical stability tests in different solvents and thin films under simulated solar light.
• Performance evaluation as a sensitizer in amorphous silicon solar cells.

Main Results:

• The molecular dyad exhibits efficient intramolecular electronic energy transfer.
• Light-induced electron transfer competes with energy transfer, affecting the acceptor's excited-state lifetime and quantum yield.
• The dyad shows slow decomposition under continuous illumination, with different degradation pathways in protic and aprotic solvents.
• Despite degradation, the molecule maintains its ability to sensitize amorphous silicon solar cells with a high turnover number (>10 million).
• The dyad's optical properties complement amorphous silicon solar cells, enhancing performance and preventing Staebler-Wronski degradation.

Conclusions:

• The investigated molecular dyad is a promising candidate for artificial light-harvesting arrays due to efficient energy transfer.
• The molecule demonstrates remarkable photostability and high turnover numbers in sensitizing silicon solar cells, even with partial degradation.
• This research highlights the potential of BODIPY-based molecular systems for advancing solar energy conversion technologies.