Spatiotemporal Exciton Tracking with a SPAD Camera.

Area of Science:

• Materials Science
• Optics
• Physical Chemistry

Background:

• Spatiotemporal microscopy is crucial for understanding exciton dynamics in light harvesting materials.
• Current techniques often require complex setups (scanning beams, delay lines), limiting accessibility.
• High resolution in both space and time is essential for accurate exciton transport studies.

Purpose of the Study:

• To develop a simplified, highly efficient spatiotemporal microscopy technique for exciton tracking.
• To overcome the limitations of existing scanning-based methods.
• To enable direct measurement of exciton diffusion without complex fitting procedures.

Main Methods:

• Implementation of a novel photoluminescence-detected exciton tracking system using a single-photon avalanche diode (SPAD) camera.
• Utilizing a SPAD camera with ∼150 ps temporal accuracy for parallel multipixel acquisition.
• Employing both point and structured illumination strategies with the SPAD camera for super-resolution excitation.

Main Results:

• The SPAD camera significantly simplifies experiments and increases photon collection efficiency by over an order of magnitude.
• Structured illumination allows direct, single-image retrieval of exciton diffusion without fitting.
• Exciton diffusion length in the organic photovoltaic material PM6 was measured at 45 nm.

Conclusions:

• The novel SPAD camera-based spatiotemporal microscopy offers a more accessible and efficient method for studying exciton dynamics.
• This technique, driven by advancements in SPAD technology, is expected to broaden the user base and applications in materials science.
• The ability to perform direct diffusion measurements simplifies analysis and accelerates research in light harvesting materials.