Transient absorption traces taken on samples of the polymer MEH-PPV are measured as a function of the laser intensity. In increasing the laser power, different decay dynamics of the signal are obtained. This suggests that effective exciton-exciton annihilation takes place. The signals are interpreted using a microscopic quantum mechanical model. The analysis points at an ultrafast excitonic decay via interchain and intrachain annihilation, where the latter process is roughly thirty times slower. Afterwards, diffusion-induced annihilation and relaxation become effective and thus determine the long-time behavior of the excited-state decay.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1039/c7cp05168a | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Excitonic Dark States in Molecular Monolayer Crystals.
Nano Lett
January 2025
School of Engineering, ANU College of Engineering, Computing and Cybernetics, The Australian National University, Canberra, ACT 2601, Australia.
The tightly bound excitons and strong dipole-dipole interactions in two-dimensional molecular crystals enable rich physics. Among them, superradiance (SR), the spontaneous coherent emission from bright excitons, has sparked considerable interest in quantum-information applications. In addition, optically forbidden states (dark exciton states) have potential to both achieve Bose-Einstein condensation and modulate exciton dynamics.
View Article and Find Full Text PDFChlorophyll to zeaxanthin energy transfer in nonphotochemical quenching: An exciton annihilation-free transient absorption study.
Proc Natl Acad Sci U S A
October 2024
Department of Chemistry, University of California, Berkeley, CA 94720.
Zeaxanthin (Zea) is a key component in the energy-dependent, rapidly reversible, nonphotochemical quenching process (qE) that regulates photosynthetic light harvesting. Previous transient absorption (TA) studies suggested that Zea can participate in direct quenching via chlorophyll (Chl) to Zea energy transfer. However, the contamination of intrinsic exciton-exciton annihilation (EEA) makes the assignment of TA signal ambiguous.
View Article and Find Full Text PDFOptically accessible long-lived electronic biexcitons at room temperature in strongly coupled H- aggregates.
Nat Commun
September 2024
Department of Chemistry, The University of Chicago, Chicago, IL, USA.
Photon absorption is the first process in light harvesting. Upon absorption, the photon redistributes electrons in the materials to create a Coulombically bound electron-hole pair called an exciton. The exciton subsequently separates into free charges to conclude light harvesting.
View Article and Find Full Text PDFLigand field exciton annihilation in bulk CrCl3.
J Chem Phys
September 2024
Organic and Carbon Electronics Laboratories, North Carolina State University, Raleigh, North Carolina 27695, USA.
The layered van der Waals material CrCl3 exhibits very strongly bound ligand field excitons that control optoelectronic applications and are connected with magnetic ordering by virtue of their d-orbital origin. Time-resolved photoluminescence of these exciton populations at room temperature shows that their relaxation is dominated by exciton-exciton annihilation and that the spontaneous decay lifetime is very long. These observations allow the rough quantification of the exciton annihilation rate constant and contextualization in light of a recent theory of universal scaling behavior of the annihilation process.
View Article and Find Full Text PDFSignatures of exciton-exciton annihilation in 2DES spectra including up to six-wave mixing processes.
J Chem Phys
September 2024
Institute of Chemical Physics, Physics Faculty, Vilnius University, Sauletekio ave. 9-III, Vilnius, Lithuania.
Two-dimensional electronic spectroscopy (2DES) is a powerful spectroscopic tool that allows us to study the dynamics of excited states. Exciton-exciton annihilation is at least a fifth order process, which corresponds to intrachromophoric internal conversion from the double-excited high-energy chromophoric state into the single-excited state of the same chromophore. At high excitation intensities, this effect becomes apparent in standard 2DES and can be inspected via high order nK1⃗-nK2⃗+K3⃗ nonlinear processes.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!