Two-dimensional electronic spectroscopy of organic semiconductor nanostructures

TL;DR

This paper uses two-dimensional electronic spectroscopy to study the quantum dynamics of squaraine-based organic semiconductor nanostructures, revealing long-range coherent exciton transport driven by plasmonic fields and showcasing their potential in hybrid nanostructures.

Contribution

It demonstrates the first time-domain analysis of exciton-plasmon couplings in squaraine nanostructures using ultrafast spectroscopy, highlighting their unique electronic properties.

Findings

Spectrally narrow J-aggregated exciton resonances in squaraine films

Long-range coherent exciton transport driven by plasmonic fields

First-time observation of coherent exciton-plasmon coupling with 10-fs resolution

Abstract

This chapter discusses recent experimental work exploring the optical properties and quantum dynamics of organic semiconductor nanostructures based on squaraine dyes. Squaraines are prototypical quadrupolar charge-transfer chromophores of interest for solu-tion-processed photovoltaics and as aggregates with large circular dichroism. Here, we demonstrate and exploit their unique properties as quantum emitters for implementing hy-brid nanostructures featuring strong exciton-plasmon couplings. We show that the unusual electronic properties of squaraines result in a substantial reduction of vibronic coupling to the ubiquitous high-frequency C-C-bond-stretching modes of organic materials and in the formation of spectrally narrow J-aggregated exciton resonances in squaraine thin films. This is exploited to create metallic nanostructures covered with squaraine thin films and to per-form the first time-domain study of coherent exciton-plasmon couplings using two-dimensional electronic spectroscopy with 10-fs time resolution. The experiments present unexpected evidence for long-range coherent exciton transport driven by plasmonic fields. This opens up new opportunities for manipulating the coherent transport of matter excita-tions by coupling to vacuum fields.