Energy relaxation and separation of a hot electron-hole pair in organic aggregates from a time-dependent wavepacket diffusion method

Han, Lu; Zhong, Xinxin; Liang, WanZhen; Zhao, Yi

doi:10.1063/1.4879955

Cited by 20 publications

(28 citation statements)

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“…[13][14][15][16][17][18][19][20][21][22] For example, Tamura and Burghardt 13 attributed fast CS to the two main factors, (i) electron delocalization within the fullerene condensate and (ii) the role of vibronically hot CT states, by carrying out a combined approach of electronic structure calculations and quantum dynamical analysis. Sun To obtain a complete description of charge dynamics it is therefore important to model the charge dynamics of both processes, "low-energy CT to CS states" and "CS to low-energy CT states", which would occur on two different timescales.…”

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Charge Dynamics in Organic Photovoltaic Materials: Interplay between Quantum Diffusion and Quantum Relaxation

2015

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Original citation:Lee, Myeong H., Aragó, Juan and Troisi, Alessandro. (2015) Charge dynamics in organic photovoltaic materials : interplay between quantum diffusion and quantum relaxation. The Journal of Physical Chemistry Part C, 119 (27). pp. 14989-14998. Permanent WRAP url:http://wrap.warwick.ac.uk/73402 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher's statement:This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry Part C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work, see http://dx.doi.org/10.1021/acs.jpcc.5b03989 A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription. For more information, please contact the WRAP This paper discusses the mechanism of generation of free charges in organic photovoltaic cells (OPV) from electrostatically bound electron-hole pairs. The efficiency of this process is explained when interfacial charge-transfer (CT) states are generated by direct optical excitation. We used semiclassical quantum dynamics at short timescale (∼100 fs) and Redfield theory at relatively long timescale (∼10-100 ps) to cover both the process of dissociation and the relaxation to the lowest energy state. Our calculations suggest that a CT state with an intermediate electron-hole separation can evolve into a charge-separated (CS) state on ultrafast timescales (∼100 fs) as a result of quantum diffusion. On long timescales, however, the CS states ultimately relax to the low-energy CT states due to the interaction with the thermal bath, indicating that the yield of free charge carrier generation is determined by the interplay between ultrafast charge separation, due to quantum diffusion, and the much slower quantum relaxation process.

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Charge Dynamics in Organic Photovoltaic Materials: Interplay between Quantum Diffusion and Quantum Relaxation

2015

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“…[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Among these, a strong candidate is the hot CT mechanism. 1, [22][23][24][25][26][27][28] In our previous study, we proposed a theoretical method to consider the hot CT state and examined the exciton dissociation process at the donor-acceptor interface. 29 The band offset of the donor-acceptor interface can provide some a) Tel.…”

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confidence: 99%

Theoretical study on the cooperative exciton dissociation process based on dimensional and hot charge-transfer state effects in an organic photocell

Shimazaki

Nakajima

2016

The Journal of Chemical Physics

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This paper discusses the exciton dissociation process at the donor-acceptor interface in organic photocells. In our previous study, we introduced a local temperature to handle the hot chargetransfer (CT) state and calculated the exciton dissociation probability based on the 1D organic semiconductor model [T. Shimazaki and T. Nakajima, Phys. Chem. Chem. Phys. 17, 12538 (2015)]. Although the hot CT state plays an essential role in exciton dissociations, the probabilities calculated are not high enough to efficiently separate bound electron-hole pairs. This paper focuses on the dimensional (entropy) effect together with the hot CT state effect and shows that cooperative behavior between both effects can improve the exciton dissociation process. In addition, we discuss cooperative effects with site-disorders and external-electric-fields. C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

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“…Recently, we have proposed a time-dependent wavepacket diffusion (TDWPD) method to describe the carrier dynamics [26][27][28][29] in organic semiconductors, which essentially incorporates the coherence and tunneling effects, and can be applied to large systems. In this article, we overview the TDWPD method and its applications.…”

Section: Introductionmentioning

confidence: 99%

Time‐dependent wavepacket diffusion method and its applications in organic semiconductors

Han

Zhong

et al. 2014

Int J of Quantum Chemistry

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Although the carriers in organic semiconductors commonly follow the hopping-type motions caused by strong carrierphonon interactions, they can also present a band-like behavior in well-performed organic crystals. In this article, we review a unified model to describe the carrier dynamics covering from the hopping-type to band-like motions, the timedependent wavepacket diffusion method proposed in our group recently. In the method, the effects of vibrational motions of organic molecules and inter or intramolecular electronic couplings are considered as the fluctuations to the carrier dynamics. Numerical simulations demonstrate that the computational cost of present method is similar to that of mixed quantum-classical methods, but it overcomes the deficiency in those methods that the detailed balance principle is not satisfied. We further present how to combine electronic structure calculations and molecular dynamics simulations with the present model to reveal the carrier dynamics in realistic organic semiconductors.

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Energy relaxation and separation of a hot electron-hole pair in organic aggregates from a time-dependent wavepacket diffusion method

Cited by 20 publications

References 54 publications

Charge Dynamics in Organic Photovoltaic Materials: Interplay between Quantum Diffusion and Quantum Relaxation

Charge Dynamics in Organic Photovoltaic Materials: Interplay between Quantum Diffusion and Quantum Relaxation

Theoretical study on the cooperative exciton dissociation process based on dimensional and hot charge-transfer state effects in an organic photocell

Time‐dependent wavepacket diffusion method and its applications in organic semiconductors

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