Carrier injection dynamics in heterojunction solar cells with bipolar molecule

Takahashi, Yosuke; Yasuda, Takeshi; Yonezawa, Kouhei; Moritomo, Yutaka

doi:10.1063/1.4914918

Cited by 3 publications

(3 citation statements)

References 27 publications

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“…Surface roughness and work function were found to be improved upon insertion of a molybdenum trioxide anode buffer layer . Carrier injection dynamics were also investigated in α‐6T/Cl‐BsubPc OPVs and found to be very slow, attributed to the migration of excitons in α‐6T …”

Section: Boron Subphthalocyaninesmentioning

confidence: 99%

Boron Subphthalocyanines and Silicon Phthalocyanines for Use as Active Materials in Organic Photovoltaics

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Josey

Sampson

et al. 2019

The Chemical Record

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Organic photovoltaics (OPVs) have experienced continued interest over the last 25 years as a viable technology for the generation of power. Phthalocyanines are among the oldest commercial dyes and have been utilized in some of the earliest examples of OPVs. In recent years, the use of boron subphthalocyanines (BsubPcs) and silicon phthalocyanines (SiPcs) has attracted a flurry of interest with some examples of fullerene‐free devices reaching power conversion efficiencies >8 %. Unlike other more common divalent phthalocyanines such as copper or zinc, BsubPcs and SiPcs contain additional axial groups that can easily be functionalized without significantly affecting the optoelectronic properties of the macrocycle. This handle facilitates our ability to tune the solid‐state arrangement and other physical characteristics such as solubility ultimately giving us the ability to improve the thin film processing and final device performance. This review covers recent studies on the development of BsubPcs and SiPcs for use as active materials in organic photovoltaics.

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Section: Boron Subphthalocyaninesmentioning

confidence: 99%

Boron Subphthalocyanines and Silicon Phthalocyanines for Use as Active Materials in Organic Photovoltaics

Grant

Josey

Sampson

et al. 2019

The Chemical Record

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“…Such a complexity of the domain structure of the BHJ layer may prevent a true understanding of the carrier formation dynamics. In this sense, a planar heterojunction (HJ) OSC with well-defined D/A interface is suitable for detailed investigation on the carrier formation and recombination dynamics [78][79][80]. For example, Moritomo et al [80] revealed carrier density effect on the carrier recombination process in PTB7/C 70 HJ solar cell.…”

Section: Donor Polymers and Small Molecules For Osc Historically Exmentioning

confidence: 99%

Carrier Formation Dynamics in Prototypical Organic Solar Cells as Investigated by Transient Absorption Spectroscopy

Moritomo

Yonezawa

Yasuda

2016

International Journal of Photoenergy

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Subpicosecond transient absorption spectroscopy is a powerful tool used to clarify the exciton and carrier dynamics within the organic solar cells (OSCs). In this review article, we introduce a method to determine the absolute numbers of the excitons and carriers against delay time (t) only from the photoinduced absorption (PIA) and electrochemically induced absorption (EIA) spectra. Application of this method to rr-P3HT-, PTB7-, and SMDPPEH-based OSCs revealed common aspects of the carrier formation dynamics. First, the temporal evolution of the numbers of the excitons and carriers indicates that the late decay component of exciton does not contribute to the carrier formation process. This is probably because the late component has not enough excess energy to separate into the electron and hole across the donor/acceptor (D/A) interface. Secondly, the spectroscopy revealed that the exciton-to-carrier conversion process is insensitive to temperature. This observation, together with the fast carrier formation time in OSCs, is consistent with the hot exciton picture.

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“…They proposed that a weakly bound electron-hole pair at the D/A interface plays a dominant role in the carrier formation process. Takahashi et al 17 investigated carrier injection dynamics in the HJ solar cell with bipolar molecule. We note that spectroscopic investigation of the HJ solar cell is further effective to separate the exciton migration and dissociation processes, because it consists of bulky A and D domains.…”

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confidence: 99%

Temperature effects on carrier formation dynamics in organic heterojunction solar cell

Yonezawa

Yasuda

Moritomo

2015

Applied Physics Letters

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The femto-second time-resolved spectroscopy was performed on the heterojunction (HJ) solar cell which consists of prototypical low-band gap donor (D), poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2b:4,5-b 0 ] dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b] thiophenediyl]] (PTB7), and the C 70 acceptor (A). We spectroscopically determined the absolute number of donor exciton (n DÃ), acceptor exciton (n AÃ), and carrier (n Dþ) per an absorbed photon against the delay time (t). At 300 K, we found that the decay time (s decay ¼ 3.5 ps) of A* is much longer than the carrier formation time (s form ¼ 1.1 ps), indicating that the late A* component does not contribute to the carrier formation process. The elongated s form (¼1.5 ps) at 80 K is ascribed to the exciton migration process, not to the exciton dissociation process. V

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Carrier injection dynamics in heterojunction solar cells with bipolar molecule

Cited by 3 publications

References 27 publications

Boron Subphthalocyanines and Silicon Phthalocyanines for Use as Active Materials in Organic Photovoltaics

Boron Subphthalocyanines and Silicon Phthalocyanines for Use as Active Materials in Organic Photovoltaics

Carrier Formation Dynamics in Prototypical Organic Solar Cells as Investigated by Transient Absorption Spectroscopy

Temperature effects on carrier formation dynamics in organic heterojunction solar cell

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