Concept of Excitons

Singh, Jai; Ruda, Harry E.

doi:10.1002/0470021942.ch4

Cited by 3 publications

(1 citation statement)

References 40 publications

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“…This situation occurs when electronic couplings throughout the system are comparable to or greater than the exciton binding energy. Our simulations show that this is conducive to charge separation, since the electron and the hole can independently travel through the material and be removed from it at external contacts, similarly to the situation in common inorganic crystalline semiconductors such as Si, Ge, and GaAs, where the exciton binding energy is smaller than the thermal energy at room temperature and is commonly neglected . It should be noted, however, that purely coherent wave function evolution can only facilitate the removal of population from eigenstates of the system Hamiltonian that are completely delocalized.…”

Section: Discussionmentioning

confidence: 61%

Coherent and Incoherent Contributions to Charge Separation in Multichromophore Systems

et al. 2015

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In organic materials, exciton dissociation into free charges requires overcoming an electron-hole Coulomb interaction that exceeds the thermal energy and may still be large after charge transfer at a donor/acceptor interface. We analyze the factors affecting efficiency of charge separation and subsequent removal of electrons and holes from such a donor-acceptor interface and suggest strategies for optimizing these processes. Energy transfer, charge separation and charge transfer in the vicinity of the donor-acceptor interface are studied within a common theoretical framework based on a quantum master equation, for a model system with realistic excitation energies and electronic couplings. We find that enhancing the efficiency of both charge transfer from the donor to the acceptor and of charge removal from the donor-acceptor interface requires an intricate balance between the extent of electronic delocalization throughout the material and rates of energy dissipation. For very large exciton binding energies, cascade charge separation in systems with more than one donor and one acceptor species, such as molecular polyads, is found to greatly facilitate the dissociation of geminate pairs. Our calculations predict charge separation on sub-picosecond timescales for several parameter combinations, leading to design principles for enhancing charge separation in multi-chromophore systems.

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Section: Discussionmentioning

confidence: 61%

Coherent and Incoherent Contributions to Charge Separation in Multichromophore Systems

et al. 2015

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Perovskites for Photovoltaics

2021

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In-situ measurement of reversible photodarkening in ion-conducting chalcohalide glass

et al. 2008

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We report the kinetics of below band-gap light induced photodarkening in (80-x)GeS(2)-20Ga(2)S(3)-xAgI (x = 0 and 20 mol %) bulk chalcogenide glasses by measuring the time evolution of transmission spectra at every 10 milliseconds. The results prove clearly the enhancement of photosensivity upon doping of AgI compound in glasses. It is interesting to find that PD observed in AgI-doped glass totally disappears two hours later after the laser exposing even at room temperature. In significant contrast to 80GeS(2)-20Ga(2)S(3) glass that the metastable part of PD remains for a long time. We expect such a fast auto-recovery property in AgI-doped glass can be utilized for optical signal processing.

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Concept of Excitons

Cited by 3 publications

References 40 publications

Coherent and Incoherent Contributions to Charge Separation in Multichromophore Systems

Coherent and Incoherent Contributions to Charge Separation in Multichromophore Systems

Perovskites for Photovoltaics

In-situ measurement of reversible photodarkening in ion-conducting chalcohalide glass

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