Efficient Photon Upconversion Enabled by Strong Coupling Between Organic Molecules and Quantum Dots

TL;DR

This paper demonstrates that converting chemical linkers to achieve strong coupling between organic molecules and quantum dots significantly enhances photon upconversion efficiency and reduces threshold intensity.

Contribution

It introduces a method to induce strong electronic coupling in hybrid structures, leading to improved photophysical performance in photon upconversion systems.

Findings

Achieved 17.2% upconversion efficiency

Lowered threshold intensity to 0.5 W/cm^2

Demonstrated strong coupling via linker chemistry

Abstract

Hybrid structures formed between organic molecules and inorganic quantum dots can accomplish unique photophysical transformations by taking advantage of their disparate properties. The electronic coupling between these materials is typically weak, leading photoexcited charge carriers to spatially localize to a dot or a molecule at its surface. However, we show that by converting a chemical linker that covalently binds anthracene molecules to silicon quantum dots from a carbon-carbon single bond to a double bond, we access a strong-coupling regime where excited carriers spatially delocalize across both anthracene and silicon. By pushing the system to delocalize, we design a photon upconversion system with a higher efficiency (17.2%) and lower threshold intensity (0.5 W/cm^2) than that of a corresponding weakly-coupled system. Our results show that strong coupling between molecules and nanostructures achieved through targeted linking chemistry provides a new route for tailoring properties in materials for light-driven applications.