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12 pages, 6895 KiB

Open AccessArticle

Organic LEDs Based on Bis(8-hydroxyquinoline) Zinc Derivatives with a Styryl Group

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Malgorzata Sypniewska

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Monika Pokladko-Kowar

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Beata Derkowska-Zielinska

Molecules 2023, 28(21), 7435; https://doi.org/10.3390/molecules28217435 - 05 Nov 2023

Viewed by 535

Abstract

For the first time, organic light-emitting diodes (OLEDs) based on bis(8-hydroxyquinoline) zinc with a styryl group (ZnStq) dispersed in poly(N-vinylcarbazole) matrix (ZnStq_R:PVK, where R = H, Cl, OCH₃) were fabricated. The ZnStq_R:PVK films made via the spin-coating method were used as [...] Read more.

For the first time, organic light-emitting diodes (OLEDs) based on bis(8-hydroxyquinoline) zinc with a styryl group (ZnStq) dispersed in poly(N-vinylcarbazole) matrix (ZnStq_R:PVK, where R = H, Cl, OCH₃) were fabricated. The ZnStq_R:PVK films made via the spin-coating method were used as the active layer in these devices. The produced OLEDs showed strong electroluminescence with yellow emissions at 590, 587 and 578 nm for the ZnStq_H:PVK, ZnStq_Cl:PVK and ZnStq_OCH₃:PVK, respectively. For all the studied thin films, the main photoluminescence emission bands were observed between 565 and 571 nm. The OLED with the ZnStq_OCH₃:PVK layer with a narrow electroluminescence spectrum was found to have sufficient color purity to produce ultra-high-resolution displays with reduced power consumption (full width at half maximum of 59 nm, maximum brightness of 2244 cd/m² and maximum current efficiency of 1.24 cd/A, with a turn-on voltage of 6.94 V and a threshold voltage of 7.35 V). To characterize the photophysical properties of the active layer, the ZnStq_R:PVK layers samples were additionally deposited on glass and silicon substrates. We found that the obtained results predestine ZnStq_R:PVK layers for use in the lighting industry in the future. Full article

(This article belongs to the Special Issue Advanced Materials for Energy and Sustainability)

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13 pages, 4101 KiB

Open AccessArticle

Characterizing Counterion-Dependent Aggregation of Rhodamine B by Classical Molecular Dynamics Simulations

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Molecules 2023, 28(12), 4742; https://doi.org/10.3390/molecules28124742 - 13 Jun 2023

Viewed by 848

Abstract

The aggregation in a solution of charged dyes such as Rhodamine B (RB) is significantly affected by the type of counterion, which can determine the self-assembled structure that in turn modulates the optical properties. RB aggregation can be boosted by hydrophobic and bulky [...] Read more.

The aggregation in a solution of charged dyes such as Rhodamine B (RB) is significantly affected by the type of counterion, which can determine the self-assembled structure that in turn modulates the optical properties. RB aggregation can be boosted by hydrophobic and bulky fluorinated tetraphenylborate counterions, such as F5TPB, with the formation of nanoparticles whose fluorescence quantum yield (FQY) is affected by the degree of fluorination. Here, we developed a classical force field (FF) based on the standard generalized Amber parameters that allows modeling the self-assembling process of RB/F5TPB systems in water, consistent with experimental evidence. Namely, the classical MD simulations employing the re-parametrized FF reproduce the formation of nanoparticles in the RB/F5TPB system, while in the presence of iodide counterions, only RB dimeric species can be formed. Within the large, self-assembled RB/F5TPB aggregates, the occurrence of an H-type RB-RB dimer can be observed, a species that is expected to quench RB fluorescence, in agreement with the experimental data of FQY. The outcome provides atomistic details on the role of the bulky F5TPB counterion as a spacer, with the developed classical FF representing a step towards reliable modeling of dye aggregation in RB-based materials. Full article

(This article belongs to the Special Issue Advanced Materials for Energy and Sustainability)

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16 pages, 4589 KiB

Open AccessArticle

Ambipolar Charge Transport in Organic Semiconductors: How Intramolecular Reorganization Energy Is Controlled by Diradical Character

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Molecules 2023, 28(12), 4642; https://doi.org/10.3390/molecules28124642 - 08 Jun 2023

Cited by 1 | Viewed by 916

Abstract

The charged forms of π–conjugated chromophores are relevant in the field of organic electronics as charge carriers in optoelectronic devices, but also as energy storage substrates in organic batteries. In this context, intramolecular reorganization energy plays an important role in controlling material efficiency. [...] Read more.

The charged forms of π–conjugated chromophores are relevant in the field of organic electronics as charge carriers in optoelectronic devices, but also as energy storage substrates in organic batteries. In this context, intramolecular reorganization energy plays an important role in controlling material efficiency. In this work, we investigate how the diradical character influences the reorganization energies of holes and electrons by considering a library of diradicaloid chromophores. We determine the reorganization energies with the four-point adiabatic potential method using quantum–chemical calculations at density functional theory (DFT) level. To assess the role of diradical character, we compare the results obtained, assuming both closed-shell and open-shell representations of the neutral species. The study shows how the diradical character impacts the geometrical and electronic structure of neutral species, which in turn control the magnitude of reorganization energies for both charge carriers. Based on computed geometries of neutral and charged species, we propose a simple scheme to rationalize the small, computed reorganization energies for both n-type and p-type charge transport. The study is supplemented with the calculation of intermolecular electronic couplings governing charge transport for selected diradicals, further supporting the ambipolar character of the investigated diradicals. Full article

(This article belongs to the Special Issue Advanced Materials for Energy and Sustainability)

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13 pages, 2993 KiB

Open AccessArticle

Dephasing Processes in the Molecular Dye Lumogen-F Orange Characterized by Two-Dimensional Electronic Spectroscopy

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Molecules 2022, 27(20), 7095; https://doi.org/10.3390/molecules27207095 - 20 Oct 2022

Viewed by 1590

Abstract

Molecular dyes are finding more and more applications in photonics and quantum technologies, such as polaritonic optical microcavities, organic quantum batteries and single-photon emitters for quantum sensing and metrology. For all these applications, it is of crucial importance to characterize the dephasing mechanisms. [...] Read more.

Molecular dyes are finding more and more applications in photonics and quantum technologies, such as polaritonic optical microcavities, organic quantum batteries and single-photon emitters for quantum sensing and metrology. For all these applications, it is of crucial importance to characterize the dephasing mechanisms. In this work we use two-dimensional electronic spectroscopy (2DES) to study the temperature dependent dephasing processes in the prototypical organic dye Lumogen-F orange. We model the 2DES maps using the Bloch equations for a two-level system and obtain a dephasing time T₂ = 53 fs at room temperature, which increases to T₂ = 94 fs at 86 K. Furthermore, spectral diffusion processes are observed and modeled by a combination of underdamped and overdamped Brownian oscillators. Our results provide useful design parameters for advanced optoelectronic and photonic devices incorporating dye molecules. Full article

(This article belongs to the Special Issue Advanced Materials for Energy and Sustainability)

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17 pages, 3893 KiB

Open AccessArticle

First-Principles-Based Optimized Design of Fluoride Electrolytes for Sodium-Ion Batteries

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Molecules 2022, 27(20), 6949; https://doi.org/10.3390/molecules27206949 - 17 Oct 2022

Cited by 1 | Viewed by 1363

Abstract

Because of the abundance and low cost of sodium, sodium-ion batteries (SIBs) are next-generation energy storage mediums. Furthermore, SIBs have become an alternative option for large-scale energy storage systems. Because the electrolyte is a critical component of SIBs, fluorination is performed to improve [...] Read more.

Because of the abundance and low cost of sodium, sodium-ion batteries (SIBs) are next-generation energy storage mediums. Furthermore, SIBs have become an alternative option for large-scale energy storage systems. Because the electrolyte is a critical component of SIBs, fluorination is performed to improve the cycling performance of electrolytes. Based on the first-principles study, we investigated the effects of the type, quantity, and relative position relationships of three fluorinated units, namely -CF₁, -CF₂, and -CF₃, on the cyclic ester molecule ethylene carbonate (EC) and the linear ether molecule 1,2-dimethoxylethane (DME). The optimal fluorination was proposed for EC and DME by studying the bond length, highest occupied molecular orbital, lowest unoccupied lowest orbital, and other relevant parameters. The results revealed that for EC, the optimal fluorination is 4 F fluorination based on four -CF₁ units; for DME, CF₃CF₁CF₁-, CF₃CF₂CF₂-, CF₃CF₁CF₂CF₃, and CF₃CF₂CF₂CF₃, four combinations of three -CF₁, -CF₂, and -CF₃ units are optimal. The designed fluorinated EC and DME exhibited a wide electrochemical stability window and high ionic solvation ability, which overcomes the drawback of conventional solvents and can improve SIB cycling performance. Full article

(This article belongs to the Special Issue Advanced Materials for Energy and Sustainability)

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13 pages, 2077 KiB

Open AccessFeature PaperArticle

Modification of the Surface Composition of PTB7-Th: ITIC Blend Using an Additive

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Molecules 2022, 27(19), 6358; https://doi.org/10.3390/molecules27196358 - 26 Sep 2022

Cited by 1 | Viewed by 1229

Abstract

We investigated the effect of adding p-anisaldehyde (AA) solvent to the ink containing poly[[2,60-4,8-di(5-ethylhexylthienyl)benzo[1,2-b:3,3-b]dithiophene][3-fluoro-2[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]](PTB7-Th) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:20,30-d0]-s-indaceno[1,2-b:5,6-b0]-dithiophene(ITIC) on the morphology of the active layer. The present study focuses on determining the effect of the additive on the compositions at the surface of the [...] Read more.

We investigated the effect of adding p-anisaldehyde (AA) solvent to the ink containing poly[[2,60-4,8-di(5-ethylhexylthienyl)benzo[1,2-b:3,3-b]dithiophene][3-fluoro-2[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]](PTB7-Th) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:20,30-d0]-s-indaceno[1,2-b:5,6-b0]-dithiophene(ITIC) on the morphology of the active layer. The present study focuses on determining the effect of the additive on the compositions at the surface of the PTB7-Th: ITIC composite and its morphology, forming one side of the interface of the blend with the MoO_X electrode, and the influence of the structural change on the performance of devices. Studies of device performance show that the addition of the additive AA leads to an improvement in device performance. Upon the addition of AA, the concentration of PTB7-Th at the surface of the bulk heterojunction (BHJ) increases, causing an increase in surface roughness of the surface of the BHJ. This finding contributes to an understanding of the interaction between the donor material and high work function electrode/interface material. The implications for the interface are discussed. Full article

(This article belongs to the Special Issue Advanced Materials for Energy and Sustainability)

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Review

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14 pages, 4241 KiB

Open AccessReview

Biomimetic Approaches to “Transparent” Photovoltaics: Current and Future Applications

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Michele Pompilio

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Ioannis Ierides

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Franco Cacialli

Molecules 2023, 28(1), 180; https://doi.org/10.3390/molecules28010180 - 25 Dec 2022

Cited by 1 | Viewed by 1155

Abstract

There has been a surge in the interest for (semi)transparent photovoltaics (sTPVs) in recent years, since the more traditional, opaque, devices are not ideally suited for a variety of innovative applications spanning from smart and self-powered windows for buildings to those for vehicle [...] Read more.

There has been a surge in the interest for (semi)transparent photovoltaics (sTPVs) in recent years, since the more traditional, opaque, devices are not ideally suited for a variety of innovative applications spanning from smart and self-powered windows for buildings to those for vehicle integration. Additional requirements for these photovoltaic applications are a high conversion efficiency (despite the necessary compromise to achieve a degree of transparency) and an aesthetically pleasing design. One potential realm to explore in the attempt to meet such challenges is the biological world, where evolution has led to highly efficient and fascinating light-management structures. In this mini-review, we explore some of the biomimetic approaches that can be used to improve both transparent and semi-transparent photovoltaic cells, such as moth-eye inspired structures for improved performance and stability or tunable, coloured, and semi-transparent devices inspired by beetles’ cuticles. Lastly, we briefly discuss possible future developments for bio-inspired and potentially bio-compatible sTPVs. Full article

(This article belongs to the Special Issue Advanced Materials for Energy and Sustainability)

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34 pages, 9977 KiB

Open AccessReview

Advances in Hybrid Composites for Photocatalytic Applications: A Review

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Stefania Porcu

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Francesco Secci

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Pier Carlo Ricci

Molecules 2022, 27(20), 6828; https://doi.org/10.3390/molecules27206828 - 12 Oct 2022

Cited by 18 | Viewed by 2992

Abstract

Heterogeneous photocatalysts have garnered extensive attention as a sustainable way for environmental remediation and energy storage process. Water splitting, solar energy conversion, and pollutant degradation are examples of nowadays applications where semiconductor-based photocatalysts represent a potentially disruptive technology. The exploitation of solar radiation [...] Read more.

Heterogeneous photocatalysts have garnered extensive attention as a sustainable way for environmental remediation and energy storage process. Water splitting, solar energy conversion, and pollutant degradation are examples of nowadays applications where semiconductor-based photocatalysts represent a potentially disruptive technology. The exploitation of solar radiation for photocatalysis could generate a strong impact by decreasing the energy demand and simultaneously mitigating the impact of anthropogenic pollutants. However, most of the actual photocatalysts work only on energy radiation in the Near-UV region (<400 nm), and the studies and development of new photocatalysts with high efficiency in the visible range of the spectrum are required. In this regard, hybrid organic/inorganic photocatalysts have emerged as highly potential materials to drastically improve visible photocatalytic efficiency. In this review, we will analyze the state-of-art and the developments of hybrid photocatalysts for energy storage and energy conversion process as well as their application in pollutant degradation and water treatments. Full article

(This article belongs to the Special Issue Advanced Materials for Energy and Sustainability)

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