Enhanced Photostability and Red‐NIR Photosensitivity of Conjugated Polymer Charge‐Transfer Complexes

Ozimova, A.E.; Bruevich, Vladimir V.; Dittrich, Thomas; Paraschuk, Dmitry Yu.

doi:10.1002/masy.201051021

Cited by 9 publications

(11 citation statements)

References 12 publications

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“…Incorporation of SE (5 wt %) resulted in a gradual decrease in band gap energies from 5.01 to 3.43 eV. The observed variation in E g with increasing SE content may be understood in terms of the formation of the stable charge transfer complexes (CTCs) between SE and PVA, which could inhibit the formation of other CTCs between the polymer and generated active oxygen species (leading to the initiation reaction of photodegradation of polymer). − Therefore, it suggested that PVA/SE should show improved photostability. On the other hand, the intramolecular interactions between PVA and melanin at the molecular level were confirmed by the FTIR analyses in our previous report …”

Section: Resultsmentioning

confidence: 99%

Simultaneous Enhancements of UV-Shielding Properties and Photostability of Poly(vinyl alcohol) via Incorporation of Sepia Eumelanin

Wang

et al. 2016

ACS Sustainable Chem. Eng.

159

136

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Sepia eumelanin (SE), a biomacromolecule, was developed to prepare the excellent UV-shielding polymer material with better photostability. UV–vis transmittance spectra showed that poly(vinyl alcohol) PVA/SE film blocked most ultraviolet light below 300 nm even with a low concentration of SE (0.5 wt %), which still kept its high transparency in the visible spectrum. Rhodamine B photodegradation measurement further confirmed the excellent UV-shielding properties of PVA/SE film. FTIR indicated that the carbonyl absorption bands resulting from phtodegradation for PVA/SE film did not change after UV exposure for 2700 h. The tensile properties of neat PVA were deceased intensely after UV irradiation; however, those of PVA/SE film were reduced a little. Moreover, AFM indicated that the surface roughness of PVA/SE film was much lower than that of a neat PVA one. It could be concluded that SE reduced the PVA degradation rate dramatically, revealing enhanced photostability of PVA/SE film. The mechanism for outstanding UV-shielding properties and photostability of PVA/SE film was illuminated, based on the formation of charge transfer complexes (CTCs) between SE and PVA, photothermal conversion, and the well-known radical scavenging capabilities of SE.

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Section: Resultsmentioning

confidence: 99%

Simultaneous Enhancements of UV-Shielding Properties and Photostability of Poly(vinyl alcohol) via Incorporation of Sepia Eumelanin

Wang

et al. 2016

ACS Sustainable Chem. Eng.

159

136

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“…[21][22][23] Charge-transfer complexes (CTC) formed between the polymer donor and acceptor molecules in the electronic ground state have already been demonstrated to be an efficient way to tune the polymer chain conformation, [24][25][26][27] phase separation in blend films, [28,29] and photooxidation stability. [30,31] Paraschuk et al [32] revealed that the CTC is likely to form when blending a small amount of the acceptor 2,4,7-trinitrofluorenone with the amorphous donor polymer poly[methoxy-5-(20-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). They pointed out that the formed CTC is highly dependent on the molecular skeletons of both the acceptor and donor polymer rather than the acceptor electron affinity and polymer concentration.…”

mentioning

confidence: 99%

Reducing Energy Disorder of Hole Transport Layer by Charge Transfer Complex for High Performance p–i–n Perovskite Solar Cells

Xue

Stuard

et al. 2021

Advanced Materials

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Charge-transport layers (CTLs), which significantly influence charge extraction and recombination, play an important role in improving photovoltaic performance of perovskite solar cells (pero-SCs). [1-3] Solution-processed organic semiconductors with versatile molecular structures, finetuned energy levels, and low-temperature processing have been intensively explored as both hole-transport materials (HTMs) and electron-transport materials (ETMs) for the pero-SCs. [4-7] However, their electronic states in thin films are dramatically affected by molecular stacking, and their weak intermolecular interactions usually have a high degree of energy disorder resulting in low carrier mobility and severe interface recombination. [8-11] Therefore, the performance of p-in pero-SCs, which is highly dependent on OS-CTLs, still lags that of n-i-p pero-SCs. [12,13] Very few OS-CTLs of pero-SCs addressing energy disorder of the CTLs were reported in the literature. Thus far, only the electron transport layer (ETL) has demonstrably reduced energy disorder by enhancing molecular ordering. Huang and co-workers [14] found that the energetic disorder in ETLs such as in [6,6]-phenyl-C 61-butyric acid methyl ester (PCBM) induced band tail and additional electronic states, leading to reduced quasi-Fermi level splitting and low efficiency. They proposed that solvent-annealed PCBM ETL with high ordering could mitigate its energy disorder and increase the power conversion efficiency (PCE) of p-in planar pero-SCs. Similarly, Miyano and co-workers [15] synthesized a highly-crystalline fullerene derivative (C 60 MC 12) to replace amorphous PCBM for enhancing the crystallization of ETL. The highly crystalline ETL could efficiently reduce energy disorder. In comparison, HTMs usually have more flexible chains required for increasing their solubility. These long and flexible chains make it difficult to improve molecular ordering through a simple external treatment, resulting in larger energy disorder and more serious surface recombination. [16] However, few attention has been paid to tuning the energy disorder of the HTL, which is likely more critical to the performance of p-in pero-SCs. Solution-processed organic semiconductor charge-transport layers (OS-CTLs) with high mobility, low trap density, and energy level alignment have dominated the important progress in p-in planar perovskite solar cells (pero-SCs). Unfortunately, their inevitable long chains result in weak molecular stacking, which is likely to generate high energy disorder and deteriorate the charge-transport ability of OS-CTLs. Here, a charge-transfer complex (CTC) strategy to reduce the energy disorder in the OS-CTLs by doping an organic semiconductor, 4,4′-(4,8-bis(5-(trimethylsilyl)thiophen-2-yl) benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(N,N-bis(4-methoxyphenyl) aniline) (BDT-Si), in a commercial hole-transport layer (HTL), poly[bis(4-phenyl) (2,4,6-trimethylphenyl)amine (PTAA), is proposed. The formation of the CTC makes the PTAA conjugated backbone electron-deficient, resulti...

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“…As Figure shows, in the blend, this intragap feature disappears, and the SPV spectrum more or less follows the blend absorption. In fact, addition of TNF to MEH-PPV extends the blend absorption into the MEH-PPV optical gap as a result of CTC formation. , …”

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confidence: 99%

Acceptor-Enhanced Local Order in Conjugated Polymer Films

Parashchuk¹,

Grigorian

Levin³

et al. 2013

J. Phys. Chem. Lett.

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Disorder in conjugated polymers is a general drawback that limits their use in organic electronics. We show that an archetypical conjugated polymer, MEH-PPV, enhances its local structural and electronic order upon addition of an electronic acceptor, trinitrofluorenone (TNF). First, acceptor addition in MEH-PPV results in a highly structured XRD pattern characteristic for semicrystalline conjugated polymers. Second, the surface roughness of the MEH-PPV films increases upon small acceptor addition, implying formation of crystalline nanodomains. Third, the low-frequency Raman features of the polymer are narrowed upon TNF addition and indicate decreased inhomogeneous broadening. Finally, the photoinduced absorption and surface photovoltage spectroscopy data show that photoexcited and dark polymer intragap electronic states assigned to deep defects disappear in the blend. We relate the enhanced order to formation of a charge-transfer complex between MEH-PPV and TNF in the electronic ground state. These findings may be of high importance to control structural properties as they demonstrate an approach to increasing the order of a conjugated polymer by using an acceptor additive.

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Enhanced Photostability and Red‐NIR Photosensitivity of Conjugated Polymer Charge‐Transfer Complexes

Cited by 9 publications

References 12 publications

Simultaneous Enhancements of UV-Shielding Properties and Photostability of Poly(vinyl alcohol) via Incorporation of Sepia Eumelanin

Simultaneous Enhancements of UV-Shielding Properties and Photostability of Poly(vinyl alcohol) via Incorporation of Sepia Eumelanin

Reducing Energy Disorder of Hole Transport Layer by Charge Transfer Complex for High Performance p–i–n Perovskite Solar Cells

Acceptor-Enhanced Local Order in Conjugated Polymer Films

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