Probing single-molecule electron-hole transfer dynamics at a molecule-NiO semiconductor nanocrystalline interface

Area of Science:

• Materials Science
• Photochemistry
• Nanotechnology

Background:

• Dye-sensitized solar cells (DSSCs) are promising for renewable energy.
• Efficient charge separation in p-type DSSCs relies on understanding interfacial charge recombination (CR).
• Limited knowledge exists on CR rates and mechanisms in NiO nanoparticle-based photocathodes.

Purpose of the Study:

• To probe interfacial charge recombination dynamics in dye-sensitized NiO nanoparticles.
• To correlate single-molecule fluorescence blinking with charge transfer dynamics.
• To elucidate the role of CR in solar energy harvesting.

Main Methods:

• Utilized single-molecule photon-stamping spectroscopy.
• Employed Zn(ii)-5,10,15,20-tetra(3-carboxyphenyl)porphyrin (m-ZnTCPP) dye-sensitized NiO nanoparticles.
• Correlated single-molecule fluorescence intensity, lifetime, and blinking dynamics.

Main Results:

• Revealed intrinsic distribution and temporal fluctuation of interfacial charge transfer reactivity.
• Demonstrated a link between CR dynamics and site-specific molecular interactions.
• Provided insights into the complex photoinduced electron and hole dynamics.

Conclusions:

• Single-molecule spectroscopy offers a powerful tool to study inhomogeneous charge transfer dynamics.
• Understanding interfacial CR is key to optimizing NiO-based photocathodes for DSSCs.
• Site-specific molecular dynamics significantly influence charge recombination processes.