Fluorination Effect for Highly Conjugated Alternating Copolymers Involving Thienylenevinylene-Thiophene-Flanked Benzodithiophene and Benzothiadiazole Subunits in Photovoltaic Application

Two two-dimensional (2D) donor–acceptor (D-A) type conjugated polymers (CPs), namely, PBDT-TVT-BT and PBDT-TVT-FBT, in which two ((E)-(4,5-didecylthien-2-yl)vinyl)- 5-thien-2-yl (TVT) side chains were introduced into 4,8-position of benzo[1,2-b:4,5-bʹ]dithiophene (BDT) to synthesize the highly conjugated electron-donating building block BDT-TVT, and benzothiadiazole (BT) and/or 5,6-difluoro-BT as electron-accepting unit, were designed to systematically ascertain the impact of fluorination on thermal stability, optoelectronic property, and photovoltaic performance. Both resultant copolymers exhibited the lower bandgap (1.60 ~ 1.69 eV) and deeper highest occupied molecular orbital energy level (EHOMO, –5.17 ~ –5.37 eV). It was found that the narrowed absorption, deepened EHOMO and weakened aggregation in solid film but had insignificant influence on thermal stability after fluorination in PBDT-TVT-FBT. Accordingly, a PBDT-TVT-FBT-based device yielded 16% increased power conversion efficiency (PCE) from 4.50% to 5.22%, benefited from synergistically elevated VOC, JSC, and FF, which was mainly originated from deepened EHOMO, increased μh, μe, and more balanced μh/μe ratio, higher exciton dissociation probability and improved microstructural morphology of the photoactive layer as a result of incorporating fluorine into the polymer backbone.

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Enhanced Photovoltaic Performance in D-π-A Copolymers Containing Triisopropylsilylethynyl-Substituted Dithienobenzodithiophene by Modulating the Electron-Deficient Units

Polymers ◽

10.3390/polym11010012 ◽

2018 ◽

Vol 11 (1) ◽

pp. 12 ◽

Cited By ~ 14

Author(s):

Junfeng Tong ◽

Lili An ◽

Jie Lv ◽

Pengzhi Guo ◽

Xunchang Wang ◽

...

Keyword(s):

Polymer Solar Cells ◽

Short Circuit ◽

Photovoltaic Performance ◽

Short Circuit Current ◽

Short Circuit Current Density ◽

Open Circuit ◽

Orbital Energy ◽

Polymer Backbone ◽

Blend Films ◽

The Impact

Three alternated D-π-A type 5,10-bis(triisopropylsilylethynyl)dithieno[2,3-d:2′,3′-d′]-benzo[1,2-b:4,5-b′]dithiophene (DTBDT-TIPS)-based semiconducting conjugated copolymers (CPs), PDTBDT-TIPS-DTBT-OD, PDTBDT-TIPS-DTFBT-OD, and PDTBDT-TIPS-DTNT-OD, bearing different A units, including benzothiadiazole (BT), 5,6-difluorinated-BT (FBT) and naphtho[1,2-c:5,6-c′]-bis[1,2,5]thiadiazole (NT), were designed and synthesized to investigate the impact of the variation in electron-deficient units on the properties of these photovoltaic polymers. It was exhibited that the down-shifted highest occupied molecular orbital energy level (EHOMO), the enhanced aggregation in both the chlorobenzene solution and the solid film, as well as the better molecular planarity, were achieved using methods involving fluorination and the replacement of BT with NT on the polymer backbone. The absorption profile was little changed upon fluorination; however, it was greatly broadened during replacement of BT with NT. Consequently, the optimized photovoltaic device based on the PDTBDT-TIPS-DTNT-OD exhibited synchronous enhancements in the open-circuit voltage (VOC) of 0.88 V, the short-circuit current density (JSC) of 7.21 mA cm−2, and the fill factor (FF) of 52.99%, resulting in a drastic elevation in the PCE by 129% to 3.37% compared to that of the PDTBDT-TIPS-DTBT-OD. This was triggered by PDTBDT-TIPS-DTNT-OD’s broadened absorption, deepened EHOMO, improved coplanarity, and enhanced SCLC mobility (which increased 3.9 times), as well as a favorable morphology of the active layer. Unfortunately, the corresponding PCE deteriorated after incorporating fluorine into the BT, due to the oversized aggregation and large phase separation morphology in the blend films, severely impairing its JSC. Our preliminary results demonstrated that the replacement of BT with NT in a D-π-A type polymer backbone was an effective strategy of tuning the molecular structure to achieve highly efficient polymer solar cells (PSCs).

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Elevated Photovoltaic Performance in Medium Bandgap Copolymers Composed of Indacenodi-thieno[3,2-b]thiophene and Benzothiadiazole Subunits by Modulating the π-Bridge

Polymers ◽

10.3390/polym12020368 ◽

2020 ◽

Vol 12 (2) ◽

pp. 368 ◽

Cited By ~ 3

Author(s):

Lili An ◽

Junfeng Tong ◽

Yubo Huang ◽

Zezhou Liang ◽

Jianfeng Li ◽

...

Keyword(s):

Conjugated Polymers ◽

Photovoltaic Performance ◽

Molecular Geometry ◽

Orbital Energy ◽

Polymer Backbone ◽

Photoactive Layer ◽

Enhanced Absorption ◽

Highest Occupied Molecular Orbital ◽

The Impact ◽

Orbital Energy Level

Two random conjugated polymers (CPs), namely, PIDTT-TBT and PIDTT-TFBT, in which indacenodithieno[3,2-b]thiophene (IDTT), 3-octylthiophene, and benzothiadiazole (BT) were in turn utilized as electron-donor (D), π-bridge, and electron-acceptor (A) units, were synthesized to comprehensively analyze the impact of reducing thiophene π-bridge and further fluorination on photostability and photovoltaic performance. Meanwhile, the control polymer PIDTT-DTBT with alternating structure was also prepared for comparison. The broadened and enhanced absorption, down-shifted highest occupied molecular orbital energy level (EHOMO), more planar molecular geometry thus enhanced the aggregation in the film state, but insignificant impact on aggregation in solution and photostability were found after both reducing thiophene π-bridge in PIDTT-TBT and further fluorination in PIDTT-TFBT. Consequently, PIDTT-TBT-based device showed 185% increased PCE of 5.84% profited by synergistically elevated VOC, JSC, and FF than those of its counterpart PIDTT-DTBT, and this improvement was chiefly ascribed to the improved absorption, deepened EHOMO, raised μh and more balanced μh/μe, and optimized morphology of photoactive layer. However, the dropped PCE was observed after further fluorination in PIDTT-TFBT, which was mainly restricted by undesired morphology for photoactive layer as a result of strong aggregation even if in the condition of the upshifted VOC. Our preliminary results can demonstrate that modulating the π-bridge in polymer backbone was an effective method with the aim to enhance the performance for solar cell.

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Fluorescent Indolo[2,3-b]quinoxalin-2-yl)(Phenyl)methanone Dyes: Photophysical, Aie Activity, Electrochemical, and Theoretical Studies

10.21203/rs.3.rs-1195228/v1 ◽

2021 ◽

Author(s):

Deepali Kanekar ◽

Sudhakar Dhanawade ◽

Anand Jadhav ◽

Mohmmed Ghadiyali ◽

Sajeev Chacko ◽

...

Keyword(s):

Thermal Stability ◽

Energy Levels ◽

Potential Candidate ◽

Good Thermal Stability ◽

Td Dft ◽

Solid Film ◽

Donor Acceptor ◽

Homo And Lumo ◽

Photophysical Studies ◽

Homo And Lumo Energy

Abstract Herein, we have synthesized four indolo[2,3-b]quinoxalin-2-yl)(phenyl)methanone derivatives 1−4 by cyclocondensation. The photophysical studies of dyes in various solvents and neat solid film exhibit typical electronic spectra with inbuilt intramolecular charge transfer (ICT) (λmax: 397‒490 nm) confirming donor-acceptor architecture. Herein, dyes fluoresce in the blue-orange region (λEmax: 435–614) on excitation at their ICT maxima in toluene, ethyl acetate, chloroform, DMSO, and neat solid film. 1 and 2 which exhibit good emission intensity in all mediums, were studied for aggregation-induced emission (AIE) effect. Electrochemical studies indicate 1−4 possess relatively low lying LUMO (‒3.65 to ‒3.98 eV) comparable to reported n-type/electron-transporting materials. The HOMO and LUMO energy levels in 1−4 were evaluated by DFT and TD-DFT calculations. TGA analysis shows 1−4 exhibit good thermal stability. The characteristic optoelectronic properties and thermal stability signify these dyes are potential candidate for their application in optoelectronics.

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Branched Electron-Donor Core Effect in D-π-A Star-Shaped Small Molecules on Their Properties and Performance in Single-Component and Bulk-Heterojunction Organic Solar Cells

Energies ◽

10.3390/en14123596 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3596

Author(s):

Alexander N. Solodukhin ◽

Yuriy N. Luponosov ◽

Artur L. Mannanov ◽

Petr S. Savchenko ◽

Artem V. Bakirov ◽

...

Keyword(s):

Solar Cells ◽

Organic Solar Cells ◽

Bulk Heterojunction ◽

Photovoltaic Performance ◽

Charge Carrier Mobility ◽

Single Component ◽

Orbital Energy ◽

Donor Acceptor ◽

And Performance ◽

Acceptor Molecules

Star-shaped donor-acceptor molecules are full of promise for organic photovoltaics and electronics. However, the effect of the branching core on physicochemical properties, charge transport and photovoltaic performance of such donor-acceptor materials in single-component (SC) and bulk heterojunction (BHJ) organic solar cells has not been thoroughly addressed. This work shows the comprehensive investigation of six star-shaped donor-acceptor molecules with terminal hexyldicyanovinyl blocks linked through 2,2′-bithiophene π-conjugated bridge to different electron-donating cores such as the pristine and fused triphenylamine, tris(2-methoxyphenyl)amine, carbazole- and benzotriindole-based units. Variation of the branching core strongly impacts on such important properties as the solubility, highest occupied molecular orbital energy, optical absorption, phase behavior, molecular packing and also on the charge-carrier mobility. The performance of SC or BHJ organic solar cells are comprehensively studied and compared. The results obtained provide insight on how to predict and fine-tune photovoltaic performance as well as properties of donor-acceptor star-shaped molecules for organic solar cells.

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The impact of thienothiophene isomeric structures on the optoelectronic properties and photovoltaic performance in quinoxaline based donor–acceptor copolymers

Polymer Chemistry ◽

10.1039/c5py00075k ◽

2015 ◽

Vol 6 (16) ◽

pp. 3098-3109 ◽

Cited By ~ 17

Author(s):

Ranbir Singh ◽

Georgia Pagona ◽

Vasilis G. Gregoriou ◽

Nikos Tagmatarchis ◽

Dimosthenis Toliopoulos ◽

...

Keyword(s):

Photovoltaic Performance ◽

Optoelectronic Properties ◽

Isomeric Structure ◽

Donor Acceptor ◽

The Impact ◽

Isomeric Structures

The importance of the monomer's isomeric structure in the design of new D–A copolymers for various applications.

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Indeno[1,2-b]fluorene-based novel donor–acceptor conjugated copolymers

High Performance Polymers ◽

10.1177/0954008316688247 ◽

2017 ◽

Vol 30 (2) ◽

pp. 192-201 ◽

Cited By ~ 3

Author(s):

Ying Sun ◽

Xiaojing Ding ◽

Xueqin Zhang ◽

Qizan Huang ◽

Baoping Lin ◽

...

Keyword(s):

Photovoltaic Performance ◽

Hole Mobility ◽

Molecular Geometry ◽

Strong Electron ◽

Photovoltaic Properties ◽

Polymer Backbone ◽

Photovoltaic Efficiency ◽

Donor Acceptor ◽

Electron Deficiency ◽

Conjugated Copolymers

A series of conjugated copolymers based on indeno[1,2-b]fluorene as donor unit with different acceptor units have been synthesized to explore the influences of molecular backbone planarization and acceptor electronegativity on charge transport and photovoltaic properties. Polymer incorporating 2,3-diphenylquinoxaline acceptor moiety shows poor light-harvesting capacity and inferior photovoltaic efficiency of 0.5% due to twisted geometry. By introducing the stronger acceptor thiadiazolo[3,4-c]pyridine in polymer, intramolecular charge transfer is enhanced, giving rise to improved absorption property and photovoltaic efficiency of 1.39%. However, the polymer backbone is still twisted. When thiophene-flanked diketopyrrolopyrrole (DPP) is incorporated as electron acceptor, the polymer exhibits a more planar molecular geometry, yielding a broader and red-shifted absorption spectrum as well as a significantly improved hole mobility of 1.46E-2 cm2 V−1 s−1. However, the photovoltaic device efficiency is only enhanced to be 1.69%. The low-lying lowest unoccupied molecular orbital of −3.95 eV as a result of the strong electron deficiency of the DPP unit may lead to the inefficient charge dissociation and increase the charge recombination, which may give rise to the limit photovoltaic performance.

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Evaluation of the Impact of Fatty Acid Methyl Ester (FAME) Contamination on the Thermal Stability of Jet A

10.21236/ada594760 ◽

2013 ◽

Author(s):

Jr Morris ◽

Shardo Robert W. ◽

Higgins James ◽

Cook Kim ◽

Tanner Rhonda ◽

...

Keyword(s):

Thermal Stability ◽

Fatty Acid ◽

Methyl Ester ◽

Fatty Acid Methyl Ester ◽

Acid Methyl Ester ◽

Acid Methyl ◽

The Impact ◽

Thermal Stability Of

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Effect of electron donor-acceptor interaction on the thermal stability of supramolecular side chain liquid crystalline polymers based on poly(3-carboxypropylmethylsiloxane)

Liquid Crystals ◽

10.1080/02678290210126040 ◽

2002 ◽

Vol 29 (5) ◽

pp. 675-685 ◽

Cited By ~ 2

Author(s):

Suat Hong Goh ◽

Yee Hing Lai

Keyword(s):

Thermal Stability ◽

Electron Donor ◽

Liquid Crystalline ◽

Liquid Crystalline Polymers ◽

Side Chain ◽

Acceptor Interaction ◽

Crystalline Polymers ◽

Donor Acceptor ◽

Thermal Stability Of

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A Novel Gemini Cationic Viscoelastic Surfactant-Based Fluid for High Temperature Well Stimulation Applications

10.2118/206297-ms ◽

2021 ◽

Author(s):

Dawn Friesen ◽

Brian Seymour ◽

Aaron Sanders

Keyword(s):

Thermal Stability ◽

High Temperature ◽

Chain Length ◽

Surfactant Concentration ◽

Gemini Surfactant ◽

Alkyl Chain ◽

Friction Reduction ◽

Fluid Viscosity ◽

Viscoelastic Surfactant ◽

The Impact

Abstract Viscoelastic surfactant (VES)-based fracturing fluids can reduce the risk of formation damage when compared with conventional polymer-based fracturing systems. However, many VES systems lose viscoelasticity rapidly under high-temperature conditions, leading to high fluid leakoff and problems in proppant placement. A gemini cationic VES-based system offering thermal stability above 250°F and its efficiency in friction reduction is presented in this paper. Rheology measurements were conducted on viscoelastic cationic gemini surfactant fluids as a function of temperature (70 – 300°F) and surfactant concentration. The length of surfactant alkyl chain was varied to investigate the impact of surfactant chain length on VES fluid viscosity at elevated temperatures. The effect of flow rate on friction reduction capability of the surfactant fluid was measured on a friction flow loop. Foam rheology measurements were conducted to evaluate the VES fluid's ability to maintain high temperature viscosity with reduced surfactant concentration. A gemini cationic surfactant was used to prepare a viscoelastic surfactant system that could maintain viscosity over 50 cP at a shear rate of 100 s−1up to at least 250°F. With this system, viscoelastic gel viscosity was maintained without degradation for over 18 hours at 250°F, and the fluid showed rapid shear recovery throughout. Decreasing the average alkyl chain length on the surfactant reduced the maximum working temperature of the resulting viscoelastic gel and showed the critical influence of surfactant structure on the resulting fluid performance. The presence of elongated, worm-like micelles in the fluid provided polymer-like friction reduction even at low surfactant concentrations, with friction reduction of over 70% observed during pumping (relative to fresh water) up to a critical Reynolds number. Energized fluids could also be formulated with the gemini surfactant to give foam fluids suitable for hydraulic fracturing or wellbore cleanouts. The resulting viscoelastic surfactant foams had viscosities over 50 cP up to at least 300°F with both nitrogen and carbon dioxide as the gas phase. The information presented in this paper is important for various field applications where thermal stability of the treatment fluid is essential. This will hopefully expand the use of VES-based systems as an alternative to conventional polymer systems in oilfield applications where a less damaging viscosified fluid system is required.

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