Related papers: Ultrafast charge-transfer exciton dynamics in C$_{…
The interaction of exciton and charge transfer (CT) states plays a central role in photo-induced CT processes in chemistry, biology and physics. In this work, we use a combination of two-dimensional electronic spectroscopy (2D-ES),…
Organic semiconducting polymers are currently of broad interest as potential low-cost materials for photovoltaic and light-emitting display applications. I will give an overview of our work in developing a consistent quantum dynamical…
We develop a theory of the electronic structure and photophysics of interacting chains of \pi- conjugated polymers to understand the differences between solutions and films. While photoexcitation generates only the intrachain exciton in…
Molecular materials have emerged as highly tunable materials for photovoltaic and light-harvesting applications. The most severe challenge of this class of materials is the trapping of charge carriers in bound electron-hole pairs, which…
Many linked processes occur concurrently in strongly excited semiconductors, such as interband and intraband absorption, scattering of electrons and holes by the heated lattice, Pauli blocking, bandgap renormalization and the formation of…
Optical excitation and control of excitonic wavepackets in organic molecules is the basis to energy conversion processes. To gain insights into such processes, it is essential to establish the relationship between the coherence timescales…
Charge-transfer (CT) exciton effects are investigated for the optical absorption spectra of crosslinked C60 systems by using the intermediate exciton theory. We consider the C60-dimers, and the two (and three) molecule systems of the…
Charge transfer states in organic semiconductors play crucial roles in processes such as singlet fission and exciton dissociation at donor/acceptor interfaces. Recently, a time-resolved spectroscopy study of…
Charge-transfer (CT) exciton effects are investigated for the optical absorption spectra of crosslinked C60 systems by using the intermediate exciton theory. We consider the C60-dimers, and the two (and three) molecule systems of the…
Efficient energy transport is highly desirable for organic semiconductor (OSC) devices such as photovoltaics, photodetectors, and photocatalytic systems. However, photo-generated excitons in OSC films mostly occupy highly localized states…
All-organic-based photovoltaic solar cells have attracted considerable attention because of their low-cost processing and short energy payback time. In such systems the primary dissociation of an optical excitation into a pair of…
The conversion of photon energy into other energetic forms in molecules is accompanied by charge moving on ultrafast timescales. We directly observe the charge motion at a specific site in an electronically excited molecule using…
We present a comparative study of ultrafast photo-conversion dynamics in tetracene (Tc) and pentacene (Pc) single crystals and Pc films using optical pump-probe spectroscopy. Photo-induced absorption in Tc and Pc crystals is activated and…
The concept of modifying molecular dynamics in strongly coupled exciton-polariton systems is an emerging topic in photonics due to its potential to produce customized chemical systems with tailored photophysical properties. However, before…
Excitons diffusing to a charge-separating interface is a necessary step to convert energy into current in next-generation photovoltaics. In this report, made possible by a new ultrafast spectrometer design, we compare exciton dynamics…
Phenomena involving electron transfer are ubiquitous in nature, photosynthesis and enzymes or protein activity being prominent examples. Their deep understanding thus represents a mandatory scientific goal. Moreover, controlling the…
Studying optical properties of organic materials is important due to the rapid development of organic light-emitting diodes, solar cells, and photon detectors. Here for the first time we have performed tight-binding calculations for singlet…
We study dynamics of incoherent exciton formation under interband photoexcitation in Cu$_2$O using time-and angle-resolved photoemission spectroscopy at 90 K. Hot electrons injected by allowed optical transitions with 3.40-eV photons show…
Long-range and fast transport of coherent excitons is important for development of high-speed excitonic circuits and quantum computing applications. However, most of these coherent excitons have only been observed in some low-dimensional…
Since the seminal work on MoS2 monolayers, photoexcitation in atomically-thin transition metal dichalcogenides (TMDCs) has been assumed to result in excitons with large binding energies (~ 200-600 meV). Because the exciton binding energies…