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10 pages, 1009 KiB

Open AccessArticle

Hybrid Lead-Halide Polyelectrolytes as Interfacial Electron Extraction Layers in Inverted Organic Solar Cells

by Jin Hee Lee, Yu Jung Park, Jung Hwa Seo and Bright Walker

Polymers 2020, 12(4), 743; https://doi.org/10.3390/polym12040743 - 27 Mar 2020

Cited by 12 | Viewed by 2498

A series of lead-halide based hybrid polyelectrolytes was prepared and used as interfacial layers in organic solar cells (OSCs) to explore their effect on the energy band structures and performance of OSCs. Nonconjugated polyelectrolytes based on ethoxylated polyethylenimine (PEIE) complexed with PbX₂ [...] Read more.

A series of lead-halide based hybrid polyelectrolytes was prepared and used as interfacial layers in organic solar cells (OSCs) to explore their effect on the energy band structures and performance of OSCs. Nonconjugated polyelectrolytes based on ethoxylated polyethylenimine (PEIE) complexed with PbX₂ (I, Br, and Cl) were prepared as polymeric analogs of the perovskite semiconductors CH₃NH₃PbX₃. The organic/inorganic hybrid composites were deposited onto Indium tin oxide (ITO) substrates by solution processing, and ultraviolet photoelectron spectroscopy (UPS) measurements confirmed that the polyelectrolytes allowed the work function of the substrates to be controlled. In addition, X-ray photoelectron spectroscopy (XPS) results showed that Pb(II) halide complexes were present in the thin film and that the Pb halide species did not bond covalently with the cationic polymer and confirmed the absence of additional chemical bonds. The composite ratio of organic and inorganic materials was optimized to improve the performance of OSCs. When PbBr₂ was complexed with the PEIE material, the efficiency increased up to 3.567% via improvements in open circuit voltage and fill factor from the control device (0.3%). These results demonstrate that lead-halide based polyelectrolytes constitute hybrid interfacial layers which provide a novel route to control device characteristics via variation of the lead halide composition. Full article

(This article belongs to the Special Issue Conjugated Oligomers and Polymer Nanomaterials)

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13 pages, 2104 KiB

Open AccessArticle

Tungsten-Doped Zinc Oxide and Indium–Zinc Oxide Films as High-Performance Electron-Transport Layers in N–I–P Perovskite Solar Cells

by Ju Hwan Kang, Aeran Song, Yu Jung Park, Jung Hwa Seo, Bright Walker and Kwun-Bum Chung

Polymers 2020, 12(4), 737; https://doi.org/10.3390/polym12040737 - 26 Mar 2020

Cited by 11 | Viewed by 4491

Abstract

Perovskite solar cells (PSCs) have attracted tremendous research attention due to their potential as a next-generation photovoltaic cell. Transition metal oxides in N–I–P structures have been widely used as electron-transporting materials but the need for a high-temperature sintering step is incompatible with flexible [...] Read more.

Perovskite solar cells (PSCs) have attracted tremendous research attention due to their potential as a next-generation photovoltaic cell. Transition metal oxides in N–I–P structures have been widely used as electron-transporting materials but the need for a high-temperature sintering step is incompatible with flexible substrate materials and perovskite materials which cannot withstand elevated temperatures. In this work, novel metal oxides prepared by sputtering deposition were investigated as electron-transport layers in planar PSCs with the N–I–P structure. The incorporation of tungsten in the oxide layer led to a power conversion efficiency (PCE) increase from 8.23% to 16.05% due to the enhanced electron transfer and reduced back-recombination. Scanning electron microscope (SEM) images reveal that relatively large grain sizes in the perovskite phase with small grain boundaries were formed when the perovskite was deposited on tungsten-doped films. This study demonstrates that novel metal oxides can be used as in perovskite devices as electron transfer layers to improve the efficiency. Full article

(This article belongs to the Special Issue Conjugated Oligomers and Polymer Nanomaterials)

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13 pages, 6900 KiB

Open AccessArticle

Effect of Donor-Acceptor Concentration Ratios on Non-Radiative Energy Transfer in Zero-Dimensional Cs₄PbBr₆ Perovskite/MEH-PPV Nanocomposite Thin Films

by Bandar Ali Al-Asbahi, Saif M. H. Qaid and Abdullah S. Aldwayyan

Polymers 2020, 12(2), 444; https://doi.org/10.3390/polym12020444 - 13 Feb 2020

Cited by 11 | Viewed by 2526

Abstract

Composite materials with different concentration ratios of a hybrid of zero-dimensional (0-D) Cs₄PbBr₆ perovskite, which acts as a donor (D), and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), which acts as an acceptor (A), were successfully prepared via a solution blending method prior to being [...] Read more.

Composite materials with different concentration ratios of a hybrid of zero-dimensional (0-D) Cs₄PbBr₆ perovskite, which acts as a donor (D), and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), which acts as an acceptor (A), were successfully prepared via a solution blending method prior to being deposited onto glass substrates by a spin-coating technique. The influence of acceptor content on the structural, optical, and energy transfer properties of the donor was investigated. The perovskite nanocrystals formed thin films without any chemical interactions within a matrix of MEH-PPV in the blend. The possibility of dipole–dipole (non-radiative) energy transfer from the 0-D Cs₄PbBr₆ to the MEH-PPV was proven. The energy transfer parameters such as R_o (critical distance of the energy transfer), k_app (apparent quenching constant),

\emptyset_{D A}

(quantum yield of D in the presence of A),

τ_{D A}

(lifetime of D in the presence of A), P_DA (probability of energy transfer), η (efficiency of energy transfer), R_DA (energy transfer radius), k_ET (energy transfer rate constant), T_DR (total decay rate), A_o (critical concentration of A), and A_π (conjugation length) were calculated based on the absorption and emission measurements. Full article

(This article belongs to the Special Issue Conjugated Oligomers and Polymer Nanomaterials)

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18 pages, 8918 KiB

Open AccessArticle

Narrowband Spontaneous Emission Amplification from a Conjugated Oligomer Thin Film

by Mohamad S. AlSalhi, Mamduh J. Aljaafreh and Saradh Prasad

Polymers 2020, 12(1), 232; https://doi.org/10.3390/polym12010232 - 17 Jan 2020

Cited by 2 | Viewed by 3185

Abstract

In this paper, we studied the laser and optical properties of conjugated oligomer (CO) 1,4-bis(9-ethyl-3-carbazo-vinylene)-9,9-dihexyl-fluorene (BECV-DHF) thin films, which were cast onto a quartz substrate using a spin coating technique. BECV-DHF was dissolved in chloroform at different concentrations to produce thin films with [...] Read more.

In this paper, we studied the laser and optical properties of conjugated oligomer (CO) 1,4-bis(9-ethyl-3-carbazo-vinylene)-9,9-dihexyl-fluorene (BECV-DHF) thin films, which were cast onto a quartz substrate using a spin coating technique. BECV-DHF was dissolved in chloroform at different concentrations to produce thin films with various thicknesses. The obtained results from the absorption spectrum revealed one sharp peak at 403 nm and two broads at 375 and 428 nm. The photoluminescence (PL) spectra were recorded for different thin films made from different concentrations of the oligomer solution. The threshold, laser-induced fluorescence (LIF), and amplified spontaneous emission (ASE) properties of the CO BECV-DHF thin films were studied in detail. The ASE spectrum was achieved at approximately 482.5 nm at a suitable concentration and sufficient pump energy. The time-resolved spectroscopy of the BECV-DHF films was demonstrated at different pump energies. Full article

(This article belongs to the Special Issue Conjugated Oligomers and Polymer Nanomaterials)

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10 pages, 2111 KiB

Open AccessArticle

Selective Ammonia-Sensing Platforms Based on a Solution-Processed Film of Poly(3-Hexylthiophene) and p-Doping Tris(Pentafluorophenyl)Borane

by Alem Araya Meresa and Felix Sunjoo Kim

Polymers 2020, 12(1), 128; https://doi.org/10.3390/polym12010128 - 05 Jan 2020

Cited by 9 | Viewed by 3667

Abstract

Here, we fabricate ammonia sensors based on organic transistors by using poly(3-hexylthiophene) (P3HT) blended with tris(pentafluorophenyl)borane (TPFB) as an active layer. As TPFB is an efficient p-type dopant for P3HT, the current level of the blend films can be easily modulated by controlling [...] Read more.

Here, we fabricate ammonia sensors based on organic transistors by using poly(3-hexylthiophene) (P3HT) blended with tris(pentafluorophenyl)borane (TPFB) as an active layer. As TPFB is an efficient p-type dopant for P3HT, the current level of the blend films can be easily modulated by controlling the blend ratio. The devices exhibit significantly increased on-state and off-state current levels owing to the ohmic current originated from the large number of charge carriers when the active polymer layer contains TPFB with concentrations up to 20 wt % (P3HT:TPFB = 8:2). The current is decreased at 40 wt % of TPFB (P3HT:TPFB = 6:4). The P3HT:TPFB blend with a weight ratio of 9:1 exhibits the highest sensing performances for various concentrations of ammonia. The device exhibits an increased percentage current response compared to that of a pristine P3HT device. The current response of the P3HT:TPFB (9:1) device at 100 ppm of ammonia is as high as 65.8%, 3.2 times that of the pristine P3HT (20.3%). Furthermore, the sensor based on the blend exhibits a remarkable selectivity to ammonia with respect to acetone, methanol, and dichloromethane, owing to the strong interaction between the Lewis acid (TPFB) and Lewis base (ammonia). Full article

(This article belongs to the Special Issue Conjugated Oligomers and Polymer Nanomaterials)

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11 pages, 2084 KiB

Open AccessArticle

Selective Wet-Etching of Polymer/Fullerene Blend Films for Surface- and Nanoscale Morphology-Controlled Organic Transistors and Sensitivity-Enhanced Gas Sensors

by Min Soo Park, Alem Araya Meresa, Chan-Min Kwon and Felix Sunjoo Kim

Polymers 2019, 11(10), 1682; https://doi.org/10.3390/polym11101682 - 15 Oct 2019

Cited by 17 | Viewed by 3558

Abstract

Surface and nanoscale morphology of thin poly(3-hexylthiophene) (P3HT) films are effectively controlled by blending the polymer with a soluble derivative of fullerene, and then selectively dissolving out the fullerene from the blend films. A combination of the polymer blending with fullerene and a [...] Read more.

Surface and nanoscale morphology of thin poly(3-hexylthiophene) (P3HT) films are effectively controlled by blending the polymer with a soluble derivative of fullerene, and then selectively dissolving out the fullerene from the blend films. A combination of the polymer blending with fullerene and a use of diiodooctane (DIO) as a processing additive enhances the molecular ordering of P3HT through nanoscale phase separation, compared to the pristine P3HT. In organic thin-film transistors, such morphological changes in the blend induce a positive effect on the field-effect mobility, as the mobility is ~5–7 times higher than in the pristine P3HT. Simple dipping of the blend films in butyl acetate (BA) causes a selective dissolution of the small molecular component, resulting in a rough surface with nanoscale features of P3HT films. Chemical sensors utilizing these morphological features show an enhanced sensitivity in detection of gas-phase ammonia, water, and ethanol. Full article

(This article belongs to the Special Issue Conjugated Oligomers and Polymer Nanomaterials)

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15 pages, 3370 KiB

Open AccessArticle

Ferrocene-Containing Conjugated Oligomers Synthesized by Acyclic Diene Metathesis Polymerization

by Xin Gao, Lei Deng, Jianfeng Hu and Hao Zhang

Polymers 2019, 11(8), 1334; https://doi.org/10.3390/polym11081334 - 12 Aug 2019

Cited by 12 | Viewed by 3490

Abstract

A series of conjugated, symmetrical, and ferrocene-containing main-chain monomers was prepared following a gentle coupling reaction. Ferrocene-containing oligomers with all-trans-configured vinylene bonds could be synthesized via acyclic diene metathesis (ADMET) polymerization. These oligomers had a larger Stokes shift (2400 to 2600 [...] Read more.

A series of conjugated, symmetrical, and ferrocene-containing main-chain monomers was prepared following a gentle coupling reaction. Ferrocene-containing oligomers with all-trans-configured vinylene bonds could be synthesized via acyclic diene metathesis (ADMET) polymerization. These oligomers had a larger Stokes shift (2400 to 2600 cm⁻¹) and both exhibited stable and reversible electrochemistry. Meanwhile, the copolymerization of 1,1’-bis[1-methyl-2-(4-vinylphenyl)ethenyl]ferrocene with 2,7-divinyl-9,9-dioctylfluorene was achieved. The structurally regular copolymers proved their optical and electrochemical properties. The fluorescence intensity of the copolymer gradually enhanced with the increasing number of fluorene units. At the same time, it was also found that the color of the copolymers had a significant change from yellow-green to red. Full article

(This article belongs to the Special Issue Conjugated Oligomers and Polymer Nanomaterials)

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Review

Jump to: Research

54 pages, 6185 KiB

Open AccessReview

Recent Innovation of Metal-Organic Frameworks for Carbon Dioxide Photocatalytic Reduction

by Alemayehu Kidanemariam, Jiwon Lee and Juhyun Park

Polymers 2019, 11(12), 2090; https://doi.org/10.3390/polym11122090 - 13 Dec 2019

Cited by 44 | Viewed by 7533

Abstract

The accumulation of carbon dioxide (CO₂) pollutants in the atmosphere begets global warming, forcing us to face tangible catastrophes worldwide. Environmental affability, affordability, and efficient CO₂ metamorphotic capacity are critical factors for photocatalysts; metal-organic frameworks (MOFs) are one of the [...] Read more.

The accumulation of carbon dioxide (CO₂) pollutants in the atmosphere begets global warming, forcing us to face tangible catastrophes worldwide. Environmental affability, affordability, and efficient CO₂ metamorphotic capacity are critical factors for photocatalysts; metal-organic frameworks (MOFs) are one of the best candidates. MOFs, as hybrid organic ligand and inorganic nodal metal with tailorable morphological texture and adaptable electronic structure, are contemporary artificial photocatalysts. The semiconducting nature and porous topology of MOFs, respectively, assists with photogenerated multi-exciton injection and adsorption of substrate proximate to void cavities, thereby converting CO₂. The vitality of the employment of MOFs in CO₂ photolytic reaction has emerged from the fact that they are not only an inherently eco-friendly weapon for pollutant extermination, but also a potential tool for alleviating foreseeable fuel crises. The excellent synergistic interaction between the central metal and organic linker allows decisive implementation for the design, integration, and application of the catalytic bundle. In this review, we presented recent MOF headway focusing on reports of the last three years, exhaustively categorized based on central metal-type, and novel discussion, from material preparation to photocatalytic, simulated performance recordings of respective as-synthesized materials. The selective CO₂ reduction capacities into syngas or formate of standalone or composite MOFs with definite photocatalytic reaction conditions was considered and compared. Full article

(This article belongs to the Special Issue Conjugated Oligomers and Polymer Nanomaterials)

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