A facile approach to synthesize an oxo-functionalized graphene/polymer composite for low-voltage operating memory devices

Wang, Zhenxing; Eigler, Siegfried; Ishii, Yoshitaka; Hu, Yichen; Papp, Christian; Lytken, Ole; Halik, Marcus

doi:10.1039/c5tc01861g

Cited by 28 publications

(24 citation statements)

References 64 publications

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“…[25] After oxidation of 1 g graphite by 2 g of potassium permanganate in concentrated sulfuric acid (97.5%), stepwise dilute of the reaction mixture and subsequent purification by hydrogen peroxide and repetitive centrifugation, an aqueous dispersion of oxo-G was obtained. [25] After oxidation of 1 g graphite by 2 g of potassium permanganate in concentrated sulfuric acid (97.5%), stepwise dilute of the reaction mixture and subsequent purification by hydrogen peroxide and repetitive centrifugation, an aqueous dispersion of oxo-G was obtained.…”

Section: Methodsmentioning

confidence: 99%

“…Figure 1b shows the chemical structure of oxo-G/DA. [25] The amino chain can promote the dispersion of oxo-G in the perovskite precursor and even form a large number of monolayer-distributed structures. The chemical structure was thoroughly investigated in an earlier study.…”

Section: The Operational Mechanism Of Oxo-g/damentioning

confidence: 99%

“…The chemical structure was thoroughly investigated in an earlier study. [23][24][25]28] The microstructure of the ultrathin nanosheets of oxo-G/DA-wrapped perovskite formed during the crystallization of perovskite can effectively reduce the defects of oxo-G/DA agglomeration formation. In several reports, we have verified the size and layer distribution of oxo-G/DA nanosheets by particle size analyzer and atomic force microscopy (AFM).…”

Section: The Operational Mechanism Of Oxo-g/damentioning

confidence: 99%

“…In this regard, ion migration inhibition can be achieved by passivating the grain boundary, regulating the crystal growth process or using additives to inhibit the movement of ions themselves. [23][24][25] The use of DA-modified oxo-G not only increases the dispersibility of oxo-G/DA in an organic solvent, which even forms a large number of single-layer nanosheets under its action. [23][24][25][26][27] Herein, we report on ultrathin 2D nanosheets of oxo-functionalized graphene/ dodecylamine (oxo-G/DA) incorporated into triple cation PSCs by solution processing, leading to high efficiency and durability.…”

Section: Introductionmentioning

confidence: 99%

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Ultrathin Nanosheets of Oxo‐functionalized Graphene Inhibit the Ion Migration in Perovskite Solar Cells

Zuo

Qiong

et al. 2019

Advanced Energy Materials

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Recent progress of PSCs in efficiency and stability enhancement is addressed to the change of perovskite composition and crystal optimization. By introducing mixed cations and halide to adjust the composition of the organicinorganic hybrid perovskite, the crystal structure of the perovskite can be effectively improved, which ultimately led to the increased stability and efficiency of the PSCs. Compared with the single cation/ halide perovskite (methylammonium halide, formamidinium lead halide, and cesium lead halide), the mixed perovskite not only has higher PCE but also has better heat and humid air stability. [9][10][11][12] For mixed cation/halide perovskites, despite good optoelectronic properties, the mixing of multiple cations and halogens is prone to localized ionic enrichment during preparation, annealing, and operation. At the same time, as the cation and halide ions move in the builtin electric field of the device, local positive and negative ion vacancies are formed. These defects will cause significant hysteresis in the device and ultimately affect the performance of the device. [13][14][15][16][17] A series of studies on both experimental and theoretical methods [13,18,19] have been reported. Constraining Mixed cation/halide perovskites have led to a significant increase in the efficiency and stability of perovskite solar cells. However, mobile ionic defects inevitably exacerbate the photoinduced phase segregation and selfdecomposition of the crystal structure. Herein, ultrathin 2D nanosheets of oxo-functionalized graphene/dodecylamine (oxo-G/DA) are used to solve ion migration in cesium (Cs)-formamidinium (FA)-methylammonium (MA) triple-cation-based perovskites. Based on the superconducting carbon skeleton and functional groups that provide lone pairs of electrons on it, the ultrathin 2D network structure can fit tightly on the crystals and wrap them, isolating them, and thus reducing the migration of ions within the built-in electric field of the perovskite film. As evidence of the formation of sharp crystals with different orientation within the perovskite film, moiré fringes are observed in transmission electron microscopy. Thus, a champion device with a power conversion efficiency (PCE) of 21.1% (the efficiency distribution is 18.8 ± 1.7%) and a remarkable fill factor of 81%, with reduced hysteresis and improved long-term stability, is reported. This work provides a simple method for the improvement of the structural stability of perovskite in solar cells.

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Section: Methodsmentioning

confidence: 99%

Section: The Operational Mechanism Of Oxo-g/damentioning

confidence: 99%

Section: The Operational Mechanism Of Oxo-g/damentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ultrathin Nanosheets of Oxo‐functionalized Graphene Inhibit the Ion Migration in Perovskite Solar Cells

Zuo

Qiong

et al. 2019

Advanced Energy Materials

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“…The reasons for this are the unique properties of graphene such as very high electrical and thermal conductivity, ultra-high carrier mobility, optical transparency, high mechanical, chemical and physical stability and many more. The most promising applications of graphene are nano-electronic devices, [1][2][3][4][5] supercapacitors, 6 solar cells, 7,8 gas sensors, 9 energy-storage materials, 10,11 in bioapplications 7,8,[12][13][14] or as a new membrane material. 15 High purity graphene obtained by mechanical exfoliation of graphite, chemical vapor deposition growth from carbon precursors or epitaxial growth on silicon carbide could not be used for large-scale applications due to its high costs.…”

Section: Introductionmentioning

confidence: 99%

High quality reduced graphene oxide flakes by fast kinetically controlled and clean indirect UV-induced radical reduction

et al. 2016

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This work highlights a surprisingly simple and kinetically controlled highly efficient indirect method for the production of high quality reduced graphene oxide (rGO) flakes via UV irradiation of aqueous dispersions of graphene oxide (GO), in which the GO is not excited directly. While the direct photoexcitation of aqueous GO (when GO is the only light-absorbing component) takes several hours of reaction time at ambient temperature (4 h) leading only to a partial GO reduction, the addition of small amounts of isopropanol and acetone (2% and 1%) leads to a dramatically shortened reaction time by more than two orders of magnitude (2 min) and a very efficient and soft reduction of graphene oxide. This method avoids the formation of non-volatile species and in turn contamination of the produced rGO and it is based on the highly efficient generation of reducing carbon centered isopropanol radicals via the reaction of triplet acetone with isopropanol. While the direct photolysis of GO dispersions easily leads to degradation of the carbon lattice of GO and thus to a relatively low electric conductivity of the films of flakes, our indirect photoreduction of GO instead largely avoids the formation of defects, keeping the carbon lattice intact.Mechanisms of the direct and indirect photoreduction of GO have been elucidated and compared.Raman spectroscopy, XPS and conductivity measurements prove the efficiency of the indirect photoreduction in comparison with the state-of-the-art reduction method for GO (hydriodic acid/trifluoroacetic acid). The rapid reduction times and water solvent containing only small amounts of isopropanol and acetone may allow easy process up-scaling for technical applications and low-energy consumption.

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Functionalization and Reduction of Graphene Oxide

Eigler¹,

Dimiev²

2016

Graphene Oxide

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A facile approach to synthesize an oxo-functionalized graphene/polymer composite for low-voltage operating memory devices

Abstract: Polystyrene-derivative wrapped oxo-functionalized graphene, prepared by controlled chemistry, can be used as a floating gate in memory devices operating at 3 V.

Cited by 28 publications

References 64 publications

Ultrathin Nanosheets of Oxo‐functionalized Graphene Inhibit the Ion Migration in Perovskite Solar Cells

Ultrathin Nanosheets of Oxo‐functionalized Graphene Inhibit the Ion Migration in Perovskite Solar Cells

High quality reduced graphene oxide flakes by fast kinetically controlled and clean indirect UV-induced radical reduction

Functionalization and Reduction of Graphene Oxide

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