Reimagining singlet exciton fission: Insights from dimer architectures

Area of Science:

• Photophysical processes
• Organic electronics
• Energy conversion

Background:

• Singlet fission (SF) is a process where one singlet excited state yields two triplet excited states, potentially doubling quantum efficiency.
• Understanding SF is crucial for efficient energy harvesting in organic solar cells.
• Controlling film morphology and molecular packing is challenging for tuning SF rates.

Purpose of the Study:

• To summarize mechanistic insights into SF from well-defined dimeric chromophore systems.
• To identify relaxation and loss pathways affecting triplet yield.
• To discuss strategies for promoting triplet dissociation and extraction from dimers.

Main Methods:

• Steady-state spectroscopic investigations.
• Time-resolved spectroscopic investigations.
• Analysis of well-defined dimeric chromophore systems.

Main Results:

• SF proceeds via a correlated triplet-triplet (TT) pair intermediate.
• Key relaxation and loss pathways can reduce effective triplet yield below 100%.
• Strategies exist to promote TT pair dissociation over annihilation in dimers.

Conclusions:

• Dimeric systems offer insights into SF mechanisms and pathways.
• Effective harvesting of triplet excitons from dimers is possible with optimized approaches.
• Further research can improve triplet exciton generation and extraction for energy applications.