Interface properties between a low band gap conjugated polymer and a calcium metal electrode

Zhang, Wei; Pan, Xiaoqing; Feng, Xuefei; Wang, Chia-Hsin; Yang, Yaw‐Wen; Ju, Huanxin; Zhu, Junfa

doi:10.1039/c5cp08066e

Cited by 4 publications

(4 citation statements)

References 54 publications

(54 reference statements)

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“…Conjugated polymers have been widely applied to optoelectronic devices, such as solar cells, field-effect transistors, polymer light-emitting diodes, and organic lasers, − because of their excellent optical and electronical properties. − In carbon-based platforms, the transport of charge carriers inside a soft film is a unique phenomenon but is considered a limiting factor in various platform applications. As such, enhanced electronically active systems have been developed.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Study on β-Phase Heredity Based on Poly(9,9-dioctylfluorene) from Solutions to Films and the Effect on Hole Mobility

Bai

Liu

et al. 2016

J. Phys. Chem. C

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In this work, the quantitative relationship in the heredity of β-phase from a solution to a thin film based on poly(9,9-dioctylfluorene) (PFO), the mechanism of β-phase formation, and the effects of β-phase contents on hole mobility were investigated. The heredity based on PFO β-phase from the solution to the thin film was characterized through UV−vis absorption. Results indicated that β-phase can be completely transferred from solutions to films during drying to form films. PFO β-phase was stable and could manage the dynamic changes from a liquid state to a thin-film state. The β-phase content was higher in the diluted solutions, and the reason was revealed through dynamic light scattering. Thus, a new structure model was constructed, and polymer chain aggregation was rendered unnecessary during PFO β-phase formation. The energy status of the β-phase was lower than that of the α-phase. Consequently, PFO chains were autonomously assembled to become orderly. The chemical environment of the low-concentration solution was more suitable than that of the high-concentration solution. The polymer chains in the former could more freely adapt to a flat geometry than those in the latter to facilitate interchain stacking. Chain aggregation was then observed through transmission electron microscopy. Photoinduced charge extraction with a linear increase in voltage was also performed to examine the charge density and hole mobility of PFO. Hole mobility could be enhanced by an order of magnitude when β-phase was increased from 0% to 5.4%. Thus, the presence of a small amount of ordered domains that can form interconnected channels could strongly enhance the carrier transport of materials in poorly ordered organic thin films, such as PFO. This condition is possibly beneficial for photoelectronic devices, and the adaptive nature of PFO chains in solutions to form a flat geometry is the main factor that promotes the order of the system.

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Section: Introductionmentioning

confidence: 99%

Quantitative Study on β-Phase Heredity Based on Poly(9,9-dioctylfluorene) from Solutions to Films and the Effect on Hole Mobility

Bai

Liu

et al. 2016

J. Phys. Chem. C

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“…As depicted in Figure d, the LUMO of CH 3 NH 3 PbI 3 locates at 0.3 eV above the Fermi level. Owing to the absence of band bending, the barrier for electron (ε e )/hole (ε h ) transport is equal to the difference between the E F and LUMO/HOMO levels . A relatively larger value of ε h (1.3 eV) as compared to that of ε e (0.3 eV) suggests that the holes are more difficult to transport at the Al/CH 3 NH 3 PbI 3 interface than the electrons.…”

Section: Results and Discussionmentioning

confidence: 99%

In Situ Investigations of Al/Perovskite Interfacial Structures

Ding

Zareen

et al. 2020

ACS Appl. Mater. Interfaces

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Interfacial properties of perovskite layers and metal electrodes play a crucial role in device performance and long-term stability of perovskite solar cells. In this work, we performed a comprehensive study of the interfacial structures and ion migration at the interface of a CH3NH3PbI3 perovskite layer and an Al electrode using in situ synchrotron radiation photoemission spectroscopy measurements. It was found that the Al electrode can react with the perovskite layers, leading to the formation of aluminum iodide species and the bonding between Al and N, as well as the reduction of Pb2+ ions to metallic Pb species at the interface. Moreover, during the Al deposition, iodide ions can migrate from the CH3NH3PbI3 subsurface to the Al electrode, while the reduced Pb remains at the subsurface. The depth profile photoemission measurements, made by varying the photon energies of incident synchrotron radiation X-rays, demonstrate that the reaction occurs at the Al/CH3NH3PbI3 interface at least with a thickness of ∼3.5 nm below the perovskite surface. This study provides an atomic-level fundamental understanding of the Al/CH3NH3PbI3 interfacial structures and insight into the degradation mechanisms of perovskite solar cells when using Al metal as the electrode.

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“…Conjugated polymers are widely applied for polymer solar cell (PSC), organic light-emitting diode, field effect transistor, and solid-state laser due to their low cost and processability. − Low-band-gap polymers used in PSCs are rapidly developing in recent years with power conversion efficiency (PCE) over 7%. − Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2- b :4,5- b ′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4- b ]thiophenediyl]] (PTB7) with structural formula shown in Figure is a kind of representative low-band-gap conjugated polymer, which is used for PSC with a certified efficiency of 9.2% . It is usually considered that OSC can be widely applied with PCE over 10%. , Therefore, extensive work has focused on PTB7 material synthesis and device fabrication to further enhance photoelectronic device performance for practical application. − …”

Section: Introductionmentioning

confidence: 99%

Dynamic Evolution from Chain Disorder to Order of PTB7 Condensed State Structures under External Fields

Ren

et al. 2018

ACS Appl. Mater. Interfaces

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In this research, the effect of external fields (solvent, temperature, solution concentration, and external force) on dynamic evolution from chain disorder to order of poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2- b:4,5- b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4- b]thiophenediyl]] (PTB7) condensed state structures was explored by UV-vis absorption spectra, atomic force microscope, and transmission electron microscopy (TEM). It was found that PTB7 main chains presented amorphous conformations induced by the poor solvent 1,2-dichloroethane. However, the local ordered aggregation appeared in amorphous conformations when the solubility of the poor solvent was again lowered by reducing temperature. It is worth noting that the size of ordered aggregation was further increased with the decrease of solution concentration or increase of external force. It was found that there were two main PTB7 absorption peaks in the UV-vis absorption spectra; we denoted A for the intensity of the lower energy absorption peak and A for the intensity of the higher energy absorption peak. The ratio R = A/ A was used to characterize the dynamic evolution from disorder to order of the PTB7 condensed state structures in absorption spectra. It increased from 0.94 for PTB7 amorphous state to 1.25 for PTB7 large-size ordered aggregation. The dynamic evolution from chain disorder to order could also be distinctly observed by TEM. It was inferred that PTB7 condensed state structures (amorphous state, local ordered aggregation, and large-scale ordered aggregation) might exist simultaneously because of the complexity of copolymer conformations. This research is meaningful to establish physical basis for the molecule design and the synthesis of materials to enhance photoelectronic device efficiency based on condensed matter physics of conjugated polymer.

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Interface properties between a low band gap conjugated polymer and a calcium metal electrode

Cited by 4 publications

References 54 publications

Quantitative Study on β-Phase Heredity Based on Poly(9,9-dioctylfluorene) from Solutions to Films and the Effect on Hole Mobility

Quantitative Study on β-Phase Heredity Based on Poly(9,9-dioctylfluorene) from Solutions to Films and the Effect on Hole Mobility

In Situ Investigations of Al/Perovskite Interfacial Structures

Dynamic Evolution from Chain Disorder to Order of PTB7 Condensed State Structures under External Fields

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