Topic
Photoexcitation
About: Photoexcitation is a research topic. Over the lifetime, 5874 publications have been published within this topic receiving 134733 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: Calculating the relaxation pathways following photoexcitation augment the original interpretation of the experimental data by providing evidence of proton transfer on the EPT state prior to decay to the ground state.
Abstract: Photoinduced concerted electron-proton transfer (EPT), denoted photo-EPT, is important for a wide range of energy conversion processes. Transient absorption and Raman spectroscopy experiments on the hydrogen-bonded p-nitrophenylphenol–t-butylamine complex, solvated in 1,2-dichloroethane, suggested that this complex may undergo photo-EPT. The experiments probed two excited electronic states that were interpreted as an intramolecular charge transfer (ICT) state and an EPT state. Herein mixed quantum mechanical/molecular mechanical nonadiabatic surface hopping dynamics is used to investigate the relaxation pathways following photoexcitation. The potential energy surface is generated on the fly with a semiempirical floating occupation molecular orbital complete active space configuration interaction method for the solute molecule and a molecular mechanical force field for the explicit solvent molecules. The free energy curves along the proton transfer coordinate illustrate that proton transfer is thermodynami...
48 citations
TL;DR: It is demonstrated that polycrystalline films of chemically identical molecules offer a promising alternative and show that photoexcitation of α-sexithiophene (α-6T) films results in efficient charge generation, leading to α- 6T based homojunction organic solar cells with an external quantum efficiency reaching up to 44% and an open-circuit voltage of 1.61 V.
Abstract: Organic solar cells usually utilise a heterojunction between electron-donating (D) and electron-accepting (A) materials to split excitons into charges. However, the use of D-A blends intrinsically limits the photovoltage and introduces morphological instability. Here, we demonstrate that polycrystalline films of chemically identical molecules offer a promising alternative and show that photoexcitation of α-sexithiophene (α-6T) films results in efficient charge generation. This leads to α-6T based homojunction organic solar cells with an external quantum efficiency reaching up to 44% and an open-circuit voltage of 1.61 V. Morphological, photoemission, and modelling studies show that boundaries between α-6T crystalline domains with different orientations generate an electrostatic landscape with an interfacial energy offset of 0.4 eV, which promotes the formation of hybridised exciton/charge-transfer states at the interface, dissociating efficiently into free charges. Our findings open new avenues for organic solar cell design where material energetics are tuned through molecular electrostatic engineering and mesoscale structural control.
48 citations
TL;DR: Both photoexcited and photoionized mechanisms for water photolysis are complementary, which is elucidated by using excited-state ab initio molecular dynamics simulations based on complete active space self-consistent field approach and unrestricted Møller-Plesset second-order perturbation theory based Born-Oppenheimer molecular dynamics simulation.
Abstract: Despite the importance of water photolysis in atmospheric chemistry, its mechanism is not well understood. Two different mechanisms for water photolysis have been proposed. The first mechanism is driven by water photoexcitation, followed by the reaction of the active hydrogen radical with water clusters. The second mechanism is governed by the ionization process. Both photoexcited and photoionized mechanisms are complementary, which is elucidated by using excited-state ab initio molecular dynamics simulations based on complete active space self-consistent field approach and unrestricted Moller-Plesset second-order perturbation theory based Born-Oppenheimer molecular dynamics simulations.
48 citations
TL;DR: In this article, the long-term photocurrent decay following the steady state photoexcitation was measured in amorphous As 2 Se 3 film as a function of temperature and the data were described empirically by the extended exponential law and are explained by dispersive diffusion-controlled recombination of excess D 0 ; 2D 0 → D + + + D −.
Abstract: The long-term photocurrent decay following the steady state photoexcitation was measured in amorphous As 2 Se 3 film as a function of temperature. The data are described empirically by the extended exponential law and are explained by dispersive diffusion-controlled recombination of excess D 0 ; 2D 0 → D + + D − .
48 citations
TL;DR: Reaction centers of Rhodobacter sphaeroides undergo a approximately 20 A3/mole volume contraction in < 50 ns after excitation, and the effective dielectric coefficient is 10-15 if the compressibility of the reaction center is similar to that of globular proteins.
48 citations