Effect of Hot-Electron Injection on the Excited-State Dynamics of a Hybrid Plasmonic System Containing Poly(3-Hexylthiophene)-Coated Gold Nanoparticles

We investigated the photophysical interaction between a conjugated polymer (CP) and a plasmonic gold nanoparticle (Au NP) using transient absorption spectroscopy. We prepared a hybrid system containing CP-stabilized Au NPs by reducing a Au precursor directly with a thiol-terminated poly(3-hexylthiophene) surfactant (P3HT-SH), with the unreacted P3HT-SH chains used as an organic matrix. The P3HT attached to the Au NPs plays two critical roles in our hybrid system: it suppresses exciton quenching from the P3HT matrix to Au NPs (the spacer role) and relays hot electrons induced by surface plasmon resonance of Au NPs to P3HT (the bridge role). Thus, singlet excitons are more slowly relaxed in our hybrid system than those in a neat P3HT film. Our findings may provide important information for development of the high-efficiency hybrid optoelectronic devices.