Control of a chemical reaction (photodegradation of the p3ht polymer) with nonlocal dielectric environments

Abstract

Proximity to metallic surfaces, plasmonic structures, cavities and other inhomogeneous dielectric environments is known to control spontaneous emission, energy transfer, scattering, and many other phenomena of practical importance. The aim of the present study was to demonstrate that, in spirit of the Marcus theory, the rates of chemical reactions can, too, be influenced by nonlocal dielectric environments, such as metallic films and metal/dielectric bilayer or multilayer structures. We have experimentally shown that metallic, composite metal/dielectric substrates can, indeed, control ordering as well as photodegradation of thin poly-3-hexylthiophene (p3ht) films. In many particular experiments, p3ht films were separated from metal by a dielectric spacer, excluding conventional catalysis facilitated by metals and making modification of the nonlocal dielectric environment a plausible explanation for the observed phenomena. This first step toward understanding of a complex relationship between chemical reactions and nonlocal dielectric environments is to be followed by the theory development and a broader scope of thorough experimental studies.

Study of the effect of excited state concentration on photodegradation of the p3ht polymer

“…The major experimental result of ref. 17 , which is most closely related to the present short communication, is as follows: The rates of photodegradation of the p3ht films deposited onto metallic or layered metal-dielectric substrates (with MgF 2 spacer on top) are smaller than those in similar p3ht films deposited onto purely dielectric substrates. This result has been interpreted as an experimental evidence of inhibition of a chemical reaction by nonlocal dielectric environment 17 .…”

“…The purpose of the present work was to study the effect of the p3ht excited state concentration on the rate of its photodegradation and answer the question whether the enhanced density of photonic states and enhanced Purcell factor in the vicinity of metamaterials and metallic surfaces can explain the result of ref. 17 discussed above.…”

“…This hypothesis has been experimentally tested in our recent work 17 , in which we studied the effect of metallic and lamellar metal-dielectric substrates on photodegradation of the poly-3-hexylthiophene (p3ht) semiconducting polymer. (The structure of p3ht, composed of thiophene rings with attached alkyl chains, as well as its absorption and emission spectra are depicted in Fig.…”

“…At the same time, one question of fundamental and practical importance has not been addressed in ref. 17 . Thus, photodegradation of organic molecules often stems from a much higher reactivity of excited molecular states than the ground state 22 .…”

Coupling of the First and Second Excited States of R6G Dye with the Fabry–Perot Cavity

“…In the former case of the weak coupling regime, transition rates are affected without noticeable change in the energy eigenvalues of the interacting systems. Arguably, this is the regime in which metamaterials with hyperbolic dispersion and metallic surfaces enhance or inhibit spontaneous emission, control Förster energy transfer, and slow down rates of chemical reactions …”