Excitation transfer and luminescence in porphyrin-carbon nanotube complexes

TL;DR

This study investigates how porphyrins attached to carbon nanotubes transfer excitation energy, leading to luminescence changes, with potential implications for optoelectronic applications.

Contribution

It demonstrates the efficient excitation transfer mechanism in porphyrin-carbon nanotube complexes using optical spectroscopy.

Findings

Red shift of 120 meV in porphyrin absorption upon binding

Strong quenching of porphyrin emission observed

Enhanced nanotube photoluminescence when excited at porphyrin absorption

Abstract

Functionalization of carbon nanotubes with hydrosoluble porphyrins (TPPS) is achieved by "$\pi$-stacking". The porphyrin/nanotube interaction is studied by means of optical absorption, photoluminescence and photoluminescence excitation spectroscopies. The main absorption line of the porphyrins adsorbed on nanotubes exhibits a 120 meV red shift, which we ascribe to a flattening of the molecule in order to optimize $\pi-\pi$ interactions. The porphyrin-nanotube complex shows a strong quenching of the TPPS emission while the photoluminescence intensity of the nanotubes is enhanced when the excitation laser is in resonance with the porphyrin absorption band. This reveals an efficient excitation transfer from the TPPS to the carbon nanotube.