Spatiotemporal Mapping Uncouples Exciton Diffusion from Singlet-Singlet Annihilation in the Electron Acceptor Y6

Area of Science:

• Optoelectronics and Nanomaterials Science
• Photophysics and Charge Transport

Background:

• Exciton transport dynamics are critical for nanostructured optoelectronic devices.
• Previous determination of the diffusion coefficient (D) for the nonfullerene electron acceptor Y6 relied on indirect singlet-singlet annihilation (SSA) experiments, potentially leading to overestimations.
• A direct method to measure exciton diffusion is needed to accurately characterize materials.

Purpose of the Study:

• To directly measure the exciton diffusion coefficient (D) in Y6 films.
• To decouple real spatial broadening from overestimations caused by SSA.
• To establish a reliable method for characterizing exciton dynamics in energy materials.

Main Methods:

• Spatiotemporally resolved photoluminescence microscopy was employed to track exciton diffusion directly.
• This technique allows for simultaneous observation of spatial and temporal exciton dynamics.
• The method overcomes limitations of indirect measurements like SSA.

Main Results:

• The diffusion coefficient (D) of Y6 was directly measured as 0.017 ± 0.003 cm²/s.
• This resulted in a Y6 film diffusion length of [specific value, if available in abstract, otherwise omit or state as 'nanometers'].
• The study successfully decoupled true spatial broadening from SSA-induced overestimation.

Conclusions:

• Spatiotemporally resolved photoluminescence microscopy provides a direct, artifact-free method for determining diffusion coefficients.
• This technique is essential for accurate characterization of exciton dynamics in materials for optoelectronic devices.
• The findings are pivotal for the future development of high-performance solar cells and other nanostructured devices.