Upconversion-Triggered Charge Separation in Polymer Semiconductors.

Area of Science:

• Optics and Photonics
• Materials Science
• Photovoltaics

Background:

• Upconversion is an optical process generating higher energy photons.
• Integrating upconverters can boost photovoltaic device efficiency by creating additional photons.
• Fundamental explanations for upconversion's contribution to photovoltaic efficiency require further investigation.

Purpose of the Study:

• To visualize the upconversion event using surface photovoltage (SPV) and Kelvin probe force microscopy (KPFM).
• To confirm the positive impact of energy transfer from upconverters to polymer semiconductors in organic solar cells (OSCs).

Main Methods:

• Utilized Kelvin probe force microscopy (KPFM) to measure surface photovoltage (SPV).
• Employed poly(3-hexyl thiophene) (P3HT) as a polymer semiconductor sensitizer.
• Investigated light upconversion events and their effect on charge carrier generation.

Main Results:

• KPFM measurements successfully visualized the upconversion event via SPV.
• Light upconversion was shown to enable the formation of charge carriers in P3HT.
• A significant SPV of -54.9 mV was observed, indicating successful energy transfer.

Conclusions:

• Upconversion positively impacts organic solar cell performance.
• Energy transfer from upconverters to P3HT is confirmed as a key mechanism for efficiency improvement.
• KPFM provides a valuable method for studying upconversion phenomena in photovoltaic materials.