Effect of polymer molecular weight on J51 based organic solar cells

Zhang, Yangqian; Xu, Xiangfei; Lu, Jiaorong; Zhang, Shiming

doi:10.1039/c9ra02022e

Cited by 8 publications

(2 citation statements)

References 41 publications

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“…[21][22][23] The absorption coefficient and vibrational level of the peaks increased progressively with molecular weights, which would be favorable for efficient charge transport and the effective use of solar photons. [24][25][26][27] The optical bandgap of the polymer samples is 1.48 eV, as established by the film absorption onsets. Besides, there is no discernible difference in the polymer batches' cyclic voltammetry (CV)-derived highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels (see Figure S3 and Table S2, Supporting Information), indicating that the molecular weight factor in PM6 has a limited influence on the frontier energy levels.…”

Section: Resultsmentioning

confidence: 99%

Viable Mixing Protocol Based on Formulated Equations for Achieving Desired Molecular Weight and Maximal Charge Separation of Photovoltaic Polymer

Lee

Kim

Nho

et al. 2021

Advanced Energy Materials

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acceptors have garnered extensive interest due to their benefits of the simple device structure, lightweight, flexibility, and low manufacturing cost using printing technologies. [1][2][3][4] Rapid material development and device-engineering advancement in the BHJ PSC community has resulted in a major increase in PSC performance over the past few decades, culminating in substantial breakthroughs in power conversion efficiencies (PCEs), which now exceed 18%. [5][6][7] Despite the success of the field of PSCs, batch-to-batch differences in molecular weight of a conjugated polymer used as one of the active layer components within a BHJ active layer, led to inconsistency in macromolecular ordering, optoelectronic and charge transport characteristics, and ultimately device performance. [8][9][10][11] There have been several attempts to overcome the molecular weight limitations caused by synthetic polymers. For example, You's and Marks's groups independently demonstrated the possibility of controlling polymer's molecular weight via a synthetic strategy based on the classic Carothers equation, considering the comonomer ratios and degree of polymerization. [12,13] We recently established a successful stepwise polymerization methodology for synthesizing high-quality polymers with narrow polydispersity and high molecular weight. [14] McCulloch et al. also isolated polymer fractions with well-defined molecular weights and narrow polydispersity using reparative-scale recycling size exclusion chromatography (rec-SEC). [15] These findings are useful in improving batch-to-batch reproducibility. To execute these technologies successfully, the reactant monomers and palladium (Pd) catalysts must be rigorously purified via multiple purification technologies and precisely weighed to ensure proper stoichiometric balance; otherwise, fractionation via the rec-SEC equipment must be tailored to the polymers produced, making it difficult to use in large-scale production. Hence, such methods are commercially inefficient and nonproductive.In this study, effective mathematical equations capable of achieving polymer batches with controlled molecule weights have been formulated. A series of PM6 donor polymers with varying molecular weights was prepared at different reaction times to verify the equations' effectiveness. Polymers with A major difficulty in the polymer solar cell (PSC) community is discovering a methodology capable of accessing polymeric photovoltaic materials with controllable/predictable molecular weights. Effective mathematical equations that enable the reproduction of polymer batches with precisely controlled molecular weight, by mixing as-synthesized polymer batches with the ones that have different molecular weights, are formulated in this study. The properties of both the as-synthesized and mixed-different-molecular weight PM6 polymer series are systematically investigated to determine the effect of molecular weight on the performance of related PSCs. The power conversion efficiencies (PCEs) improve monotonically with an i...

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Section: Resultsmentioning

confidence: 99%

Viable Mixing Protocol Based on Formulated Equations for Achieving Desired Molecular Weight and Maximal Charge Separation of Photovoltaic Polymer

Lee

Kim

Nho

et al. 2021

Advanced Energy Materials

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show abstract

“…For photovoltaic polymers, there are a great deal of studies about the correlation between the molecular weight (Mw) and photovoltaic performance, and different molecular weights can lead to significant variations in solubility, , optical–electricity property, , molecular orientation, , charge mobilities, device series resistance, charge recombination, , and final PCE. In general, a higher Mw of the polymer is considered to be related to better photovoltaic performance, ,− while some studies have shown that medium Mw − and low Mw , are conducive to higher PCE.…”

Section: Introductionmentioning

confidence: 99%

Improving the Photovoltaic Performance of Dithienobenzodithiophene-Based Polymers via Addition of an Additional Eluent in the Soxhlet Extraction Process

Zhou

Guo

Bao

et al. 2022

ACS Appl. Mater. Interfaces

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Dithieno[2,2′,benzo [1,2-b;4,5-b′]dithiophene (DTBDT) is a kind of pentacyclic aromatic electrondonating unit with unique optoelectronic properties, but it has received less attention in the design of photovoltaic polymers. In this work, we copolymerized DTBDT with the electron-deficient unit of dithieno [3′,2′:3,4;2″,3″:5,6]benzo[1,2-c][1,2,5]thiadiazole (DTBT) and obtained two polymers, PE55 and PE56, with a synergistic heteroatom substitution strategy. When blended with the classic nonfullerene acceptor Y6, PE55 and PE56 achieve power conversion efficiencies (PCEs) of 13.78% and 14.49%, respectively, which indicates that the introduction of sulfur atoms on the conjugated side chain of the D unit is a promising method to enhance the performance of DTBDT-based polymers. Besides, we utilize dichloromethane and chloroform to separate the low molecular weight (Mw) fractions in the solvent extraction process to obtain PE55-CF and PE56-CB, and the PCEs are further improved to 15.00% and 16.11%, respectively. The stronger π−π stacking, optimized blend film morphology, and higher charge mobilities contribute to the enhanced PCEs for polymers with higher Mw obtained via the multistep solvent extraction strategy. Our results not only provide a simple and effective way to improve the photovoltaic performance of conjugated polymers but also imply that some reported polymers purified from the traditional one-step solvent extraction method might be seriously underestimated.

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Active Layer Morphology Engineering of All-polymer Solar Cells by Systematically Tuning Molecular Weights of Polymer Donors/Acceptors

Wang

Zhao

et al. 2021

Chin J Polym Sci

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Effect of polymer molecular weight on J51 based organic solar cells

Abstract: Very recently, organic solar cells (OSCs) have achieved outstanding scientific results with a power conversion efficiency (PCE) of over 16%.

Cited by 8 publications

References 41 publications

Viable Mixing Protocol Based on Formulated Equations for Achieving Desired Molecular Weight and Maximal Charge Separation of Photovoltaic Polymer

Viable Mixing Protocol Based on Formulated Equations for Achieving Desired Molecular Weight and Maximal Charge Separation of Photovoltaic Polymer

Improving the Photovoltaic Performance of Dithienobenzodithiophene-Based Polymers via Addition of an Additional Eluent in the Soxhlet Extraction Process

Active Layer Morphology Engineering of All-polymer Solar Cells by Systematically Tuning Molecular Weights of Polymer Donors/Acceptors

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