نتایج جستجو برای: charge recombination
تعداد نتایج: 186940 فیلتر نتایج به سال:
The influence of the excitation pulse carrier frequency on the ultrafast charge recombination dynamics of excited donor-acceptor complexes has been explored both theoretically and experimentally. The theoretical description involves the explicit treatment of both the optical formation of the nuclear wave packet on the excited free energy surface and its ensuing dynamics. The wave packet motion ...
Low-bandgap diketopyrrolopyrrole- and carbazole-based polymer bulk-heterojunction solar cells exhibit much faster charge carrier recombination kinetics than that encountered for less-recombining poly(3-hexylthiophene). Solar cells comprising these polymers exhibit energy losses caused by carrier recombination of approximately 100 mV, expressed as reduction in open-circuit voltage, and consequen...
Bismuth vanadate is one of the most promising photoanode materials for photoelectrochemical water splitting. In order to achieve high photocurrents the surface of BiVO4 always has to be modified with water oxidation catalysts, such as cobalt phosphate (CoPi), FeOOH, or NiFeO x . While this has generally been attributed to the poor intrinsic catalytic activity of BiVO4, detailed insight into the...
Unambiguous evidence for the formation of excited ions upon ultrafast bimolecular photoinduced charge separation is found using a combination of femtosecond time-resolved fluorescence up-conversion, infrared and visible transient absorption spectroscopy. The reaction pathways are tracked by monitoring the vibrational energy redistribution in the product after charge separation and subsequent ch...
Excitation wavelength dependent femtosecond transient photocurrents were measured on CuIn(S,Se)2 solar cell devices, in the range of 330–1300 nm. Below 450 nm wavelength excitations, charge recombination in CdS/ZnO layers is determined to be responsible for longer decays and lower EQE. Femtosecond pump–probe measurements also support the charge transfer and recombination in CdS/ZnO layers. Thes...
The photophysical and electrochemical properties of a dyad comprising an expanded acridinium light-harvester, coupled via a triple bond to a trialkyloxybenzene donor, are described. Laser excitation of the dyad in 1,2-dichloroethane (DCE) results in rapid charge shift (5 ps) followed by slower charge recombination (81 ps) to completely restore the ground state. Discrimination between forward an...
To minimize the charge recombination between electrons and the electron acceptor in solid-state dye-sensitized solar cells, we propose a separated electron donor and acceptor of a redox couple in the photoanode and in the cathode, respectively. Owing to the absence of the acceptor in the photoanode initially, the charge recombination rate is retarded remarkably, resulting in an increase of the ...
Time-resolved hard X-ray photoelectron spectroscopy (trHAXPES) using microfocused X-ray free-electron laser (XFEL, hν = 8 keV) pulses as a probe and infrared laser pulses (hν = 1.55 eV) as a pump is employed to determine intrinsic charge-carrier recombination dynamics in La:SrTiO3. By means of a combination of experiments and numerical N-body simulations, we first develop a simple approach to c...
Among the parameters that characterize a solar cell and define its power-conversion efficiency, the fill factor is the least well understood, making targeted improvements difficult. Here we quantify the competition between charge extraction and recombination by using a single parameter θ, and we demonstrate that this parameter is directly related to the fill factor of many different bulk-hetero...
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