Fundamental processes of exciton scattering at organic solar-cell interfaces: One-dimensional model calculation

Masugata, Yoshimitsu; Iizuka, Hideyuki; Sato, Kosuke; Nakayama, Takashi

doi:10.7567/jjap.55.081601

Cited by 2 publications

(3 citation statements)

References 39 publications

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“…The wave packet moves following the Schrödinger equation, and the tunneling probability is obtained as a probability of scattered (tunneled) wave packet located in the conduction-band states in the right n-Si region. 32,33) As an initial wave packet at time t = 0, we set the δfunction-shaped packet at n = −80 site (x 40 nm = -…”

Section: Calculation Model and Methodsmentioning

confidence: 99%

Resonance-enhanced tunneling current through Si-p/n junction with additional dopants: theoretical study

Cho

Iizuka

Nakayama

2019

Jpn. J. Appl. Phys.

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The tunneling probability of electrons through a Si-p/n junction with additional dopants is calculated by the time evolution of wave packets using the simple one-dimensional tight-binding model. It was shown that the probability is markedly enhanced, being consistent with experiments. We showed that such enhancement is caused by the resonance between the isolated dopant electronic state and continuous conduction-or valenceband states of host Si in the junction. Moreover, we demonstrate that the probability strongly depends on the spatial and energy positions of the dopant electronic state. © 2019 The Japan Society of Applied Physics c c g = | | In particular, direct and indirect band-gap structures are produced using the negative and positive values for , c g respectively, together with the positive . v g Namely, the valence-band top and conduction-band bottom are located at the Γ point, i.e., the center of Brillouin zone with the Bloch wave number of k = 0, when v g > 0 and c g < 0, while they are, respectively, located at the Γ point and the boundary of Brillouin zone when v g > 0 and c g > 0. The second term describes the on-site energy b n , e of the b-band at the n site. To realize the p/n junction under the applied electric field, b n , e depends on the position of the site as

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Section: Calculation Model and Methodsmentioning

confidence: 99%

Resonance-enhanced tunneling current through Si-p/n junction with additional dopants: theoretical study

Cho

Iizuka

Nakayama

2019

Jpn. J. Appl. Phys.

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“…Several models have been proposed to account for the charge-separation process according to experimental and theoretical studies. − In the most common model, the exciton created in the donor bulk diffuses to the interface where it decays nonadiabatically into strongly bound interfacial charge-transfer (CT) states. To realize charge separation, excess energy, such as thermal energy and electric field, is required to lift the system up into high-energy long-range charge-separated (CS) states whose electrons and holes are weakly bound.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Masugata et al. propose that scattering of donor excitons by the interface might result in exciton dissociation …”

Section: Introductionmentioning

confidence: 99%

Different Dissociation Rates of Singlet and Triplet Excitons of Pentacene at the Interface in Solar Cells

et al. 2019

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Fission of the lowest-energy singlet exciton (S1) to two lowest-energy triplet excitons (T1) in pentacene has been expected to be a promising means for increasing the quantum efficiency of solar cells. Experiments find that S1 and T1 dissociate at quite different time scales at the donor/acceptor interface. Using the pentacene/TiO2 heterojunction as the model, we investigate the dissociation of pentacene excitons by a combination of many-body Green’s function theory and the time-dependent Schrödinger equation. Singlet and higher-energy triplet (T n ) excitons of pentacene could dissociate at the same timescale of ∼100 fs, benefiting from their capability to scatter into charge-transfer (CT) states and weakly bound charge-separated (CS) states across the interface. Resonance of pentacene excitons with CS states could facilitate the creation of free charge carriers. However, dissociation of T1 is hampered due to its poor density of states projected onto the interfacial states, preventing its scattering into CT and CS states. According to this phenomenon, we suspect that the electron transfer from T1 to acceptor, as observed in experiments, might undergo two successive processes, promotion of T1 to T n by visible light and dissociation of T n via scattering. Involvement of the additional light absorption process might result in the low dissociation rate of T1.

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Fundamental processes of exciton scattering at organic solar-cell interfaces: One-dimensional model calculation

Cited by 2 publications

References 39 publications

Resonance-enhanced tunneling current through Si-p/n junction with additional dopants: theoretical study

Resonance-enhanced tunneling current through Si-p/n junction with additional dopants: theoretical study

Different Dissociation Rates of Singlet and Triplet Excitons of Pentacene at the Interface in Solar Cells

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