Binary small molecule organic nanoparticles exhibit both direct and diffusion-limited ultrafast charge transfer with NIR excitation

Kudisch, Bryan; Maiuri, Margherita; Wang, Leon; Lim, Tristan; Lu, Hoang D.; Lee, Victoria; Prud'homme, Robert Krafft; Scholes, Gregory D.

doi:10.1039/c8nr09619h

Cited by 4 publications

(7 citation statements)

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“…3. Upon nanoparticle formation using flash nanoprecipitation (39,40), the CuPc spectrum starkly blue-shifts by 70 nm and broadens, giving rise to a new excitonic absorption band due to the strong intermolecular interactions concomitant with molecular aggregation, characteristic of H-aggregates. This absorption spectrum differs from the absorption spectra of many recorded CuPc thin films and single crystals because of the lack of crystallinity in the nanoparticle samples (41).…”

Section: Resultsmentioning

confidence: 99%

“…In order to form the phthalocyanine nanoparticles, the phthalocyanines and an amphiphilic stabilizer, here polystyrene blocked in this work with polyethylene glycol (PS-b-PEG, 5k-1.6k) were codissolved in THF, a water-miscible organic solvent. Through micromixing of the phthalocyanine-block copolymer solution with Milli-Q deionized water using a confined impinging jet reactor, the phthalocyanines precipitate in the aqueous environment and are stabilized by the amphiphilic block copolymer to form organic nanoparticles, in a process known as flash nanoprecipitation (39,40,54,55). The mixed streams were then diluted 10-fold into an aqueous collecting solvent and used after dialysis to remove the remaining THF.…”

Section: Methodsmentioning

confidence: 99%

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Ring currents modulate optoelectronic properties of aromatic chromophores at 25 T

Kudisch

Maiuri

Moretti

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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The properties of organic molecules can be influenced by magnetic fields, and these magnetic field effects are diverse. They range from inducing nuclear Zeeman splitting for structural determination in NMR spectroscopy to polaron Zeeman splitting organic spintronics and organic magnetoresistance. A pervasive magnetic field effect on an aromatic molecule is the aromatic ring current, which can be thought of as an induction of a circular current of π-electrons upon the application of a magnetic field perpendicular to the π-system of the molecule. While in NMR spectroscopy the effects of ring currents on the chemical shifts of nearby protons are relatively well understood, and even predictable, the consequences of these modified electronic states on the spectroscopy of molecules has remained unknown. In this work, we find that photophysical properties of model phthalocyanine compounds and their aggregates display clear magnetic field dependences up to 25 T, with the aggregates showing more drastic magnetic field sensitivities depending on the intermolecular interactions with the amplification of ring currents in stacked aggregates. These observations are consistent with ring currents measured in NMR spectroscopy and simulated in time-dependent density functional theory calculations of magnetic field-dependent phthalocyanine monomer and dimer absorption spectra. We propose that ring currents in organic semiconductors, which commonly comprise aromatic moieties, may present new opportunities for the understanding and exploitation of combined optical, electronic, and magnetic properties.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Ring currents modulate optoelectronic properties of aromatic chromophores at 25 T

Kudisch

Maiuri

Moretti

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…For example, the performance of solar cells and transistors was boosted by employing bulk heterojunction with interpenetrating networks of donor and acceptor materials that address the bottleneck in excitation diffusion, trigger the quantum well effect, and increase electron mobility . Inspired by these effects, a bulk heterojunction structure is recommended as the active layer to enhance the conductivity and efficiency of generating charges from photons in nonvolatile memory device …”

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confidence: 99%

“…It is has low cost, good film‐forming ability, good adherence to various substrates, a deeper highest occupied molecular orbital (HOMO) level, and a higher hole mobility and conductivity. PCBM is widely used in solar cell to compose organic bulk heterojunction . These two materials are mature and commercially available, avoiding complex synthesis in their production.…”

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confidence: 99%

“…[29,30] Inspired by these effects, a bulk heterojunction structure is recommended as the active layer to enhance the conductivity and efficiency of generating charges from photons in nonvolatile memory device. [31][32][33][34] We utilized organic bulk heterojunction in RRAMs to implement ternary memory with improved stability and device yield. X55 [35] is a new hole-transport material for use in organic solar cells.…”

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confidence: 99%

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Flexible Ternary Resistive Memory from Organic Bulk Heterojunction

Zhao

Sun

Wang

et al. 2019

Adv Materials Technologies

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planarity, better crystallinity, [14,15] and lower schottky barrier [16][17][18] and more compact contact with electrodes; [18][19][20] however, it remains difficult to achieve satisfactory performance solely from molecular formula innovation.Recently, solar cells, transistors, and diodes are significantly improved by introduction of donor-acceptor heterojunctions with suitable electronic properties. [12,[20][21][22][23][24][25] For example, the performance of solar cells and transistors was boosted by employing bulk heterojunction with interpenetrating networks of donor and acceptor materials that address the bottleneck in excitation diffusion, [12,26] trigger the quantum well effect, [27][28][29] and increase electron mobility. [29,30] Inspired by these effects, a bulk heterojunction structure is recommended as the active layer to enhance the conductivity and efficiency of generating charges from photons in nonvolatile memory device. [31][32][33][34] We utilized organic bulk heterojunction in RRAMs to implement ternary memory with improved stability and device yield. X55 [35] is a new hole-transport material for use in organic solar cells. It is has low cost, good film-forming ability, good adherence to various substrates, a deeper highest occupied molecular orbital (HOMO) level, and a higher hole mobility and conductivity. PCBM is widely used in solar cell to compose organic bulk heterojunction. [34] These two materials are mature and commercially available, avoiding complex synthesis in their production. We used X55 and PCBM to construct an organic heterojunction aiming to improve memory device yield. Ternary memory yield of device from the blend of X55 and PCBM with 1:1 molar ratio is 58%, higher than that of pure X55, PCBM, or layer-by-layer stacking thereof. [38] Furthermore, the mixture was made on a flexible substrate, and was able to sustain its memory performance after 5000 bending cycles at a bending angle of 62°. Our work stimulates the new concept of active material design in n-nary RRAM devices.There are three main steps in the fabrication of ternary RRAM devices with a sandwich-like structure of ITO glass /active layers (80-200 nm)/Al (top electrode 80 nm). ITO glasses were first sonicated in acetone, deionized water, and ethanol for 10 min. Then, active layer materials of X55, PCBM (Figure 1a) were drop-casted onto ITO glasses, followed by annealing at 60 °C in vacuum. An array of top electrodes was deposited on the films through thermal evaporation of Al, forming the structure revealed by scanning electron imaging of the cross-section of Organic ternary resistive memory suffers from low device yield and wide writing voltage distribution and improvement through laborious molecular formula innovation is limited. Here, organic bulk heterojunction is employed as the active material in resistive random-access memories (RRAMs). The ternary memory yield of the device reaches 58% when prepared by blending X55 (N2, 7-bis(4-methoxyphenyl)N2, N7-bis (2-spiro [fluorene-9,9′oxanthracene]-spiro[fluorene-9,9′-...

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Flash technology-based self-assembly in nanoformulation: Fabrication to biomedical applications

Yang

et al. 2021

Materials Today

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Binary small molecule organic nanoparticles exhibit both direct and diffusion-limited ultrafast charge transfer with NIR excitation

Abstract: We report the facile synthesis on new binary organic nanoparticles composed of NIR absorbing small molecules, which we show using ultrafast spectroscopy undergo photoinduced electron transfer.

Cited by 4 publications

References 40 publications

Ring currents modulate optoelectronic properties of aromatic chromophores at 25 T

Ring currents modulate optoelectronic properties of aromatic chromophores at 25 T

Flexible Ternary Resistive Memory from Organic Bulk Heterojunction

Flash technology-based self-assembly in nanoformulation: Fabrication to biomedical applications

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