Impact of the Nature of the Side‐Chains on the Polymer‐Fullerene Packing in the Mixed Regions of Bulk Heterojunction Solar Cells

Wang, Tonghui; Ravva, Mahesh Kumar; Brédas, Jean‐Luc

doi:10.1002/adfm.201601134

Cited by 46 publications

(74 citation statements)

References 34 publications

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“…We attributed this difference to two possible effects. 50 The authors systematically investigated the For TQ1, shown in Figure 4e, it can be seen that there is a clear preference (sharper peak) for PCBM-A as opposed to PCBM-D stacking. The second is that the inadequacy of treating the conjugated carbon atoms with a standard Lennard-Jones potential due to extended π-conjugation.…”

Section: Intermolecular Melt-phase Structurementioning

confidence: 99%

Modelling the morphology and thermomechanical behaviour of low-bandgap conjugated polymers and bulk heterojunction films

Root

Jackson

Savagatrup

et al. 2017

Energy Environ. Sci.

102

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PAPER Félix Urbain et al. Multijunction Si photocathodes with tunable photovoltages from 2.0 V to 2.8 V for light induced water splitting This paper describes the use of molecular dynamics (MD) to predict the nanoscale morphology and thermomechanical behavior of three low-bandgap semiconducting polymers and their blends with PC71BM. While the three polymers modeled in this study-PTB7, PDTSTPD, and TQ1-all exhibit the donor-acceptor motif characteristic of high-performance donor materials in organic solar cells, they exemplify different morphologies in the solid state. Predictions from the atomistic simulations presented here include the average conjugation length of the polymers, the structural arrangement of conjugated donor and acceptor units in neat and bulk heterojunction (BHJ) films, as well as the glass transition temperature and tensile modulus of neat and BHJ polymer films. Calculated tangent correlation functions exhibit oscillatory decay. This finding suggests that DA polymers are more appropriately modeled as ribbon-like chains as opposed to worm-like chains. To account for the range of morphologies accessible by processing manipulations, both a meltquenched and a self-aggregated morphology are prepared. Owing to the greater free volume of the self-aggregated morphology, these solid structures are found to be softer and weaker than the melt-quenched morphologies. The experimental modulus measured previously for PDTSTPD is similar to the predicted self-aggregated morphology, while the experimental modulus of PTB7 is similar to the predicted melt-quenched modulus. Our comparisons with experiment suggest that solution-processing plays a critical role in optimizing the mechanical properties of conjugated polymeric materials. Overall, the results of this study suggest the promise of MD simulations in determining the ways in which molecular structure influence the morphology and mechanical properties of bulk heterojunction films for solar cells and other organic electronic devices.

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Section: Intermolecular Melt-phase Structurementioning

confidence: 99%

Modelling the morphology and thermomechanical behaviour of low-bandgap conjugated polymers and bulk heterojunction films

Root

Jackson

Savagatrup

et al. 2017

Energy Environ. Sci.

102

View full text Add to dashboard Cite

show abstract

“…However, the low fill factor is likely a result of this high degree of disorder in the film, and may be a limitation for highly disordered OPV materials. One route to improve the PCE of this structure is through side chain tuning, as this has been shown to have a significant impact on polymer/fullerene mixing . Polymers P1–P4 were not considered for OPV cells due to their high bandgaps.…”

Section: Resultsmentioning

confidence: 99%

Multifunctional triphenylamine polymers synthesized via direct (hetero) arylation polymerization

Schmatz

Ponder

Reynolds

2017

J. Polym. Sci. Part A: Polym. Chem.

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The design rules for creating multifunctional organic electronic materials are currently limited. By copolymerizing twisted triphenylamine (TPA) and electron rich dioxythiophene (XDOT) monomers via Direct (Hetero) Arylation Polymerization (DHAP), a set of polymers are obtained that perform as yellow to transmissive electrochromic (EC) films with up to 45% contrast, as well as in electroluminescent (EL) applications, achieving a luminance of 450 cd/m 2 in yellowgreen polymer light-emitting diodes (PLEDs). In addition, polymerizing TPA with a donor-acceptor-donor monomer results in a low-bandgap polymer that achieves power conversion efficiencies up to 2.5% when blended with PC 71 BM in conventional organic photovoltaic (OPV) devices. Incorporation of TPA units into the polymer backbone largely breaks any aggregation and ordering in the solid-state, leading to highly soluble materials that form smooth, reproducible thin films. The TPA unit also serves to break conjugation throughout the polymer backbone, providing precise control over optical and electronic properties through choice of comonomer. These results suggest that TPA copolymers can be useful for achieving multi-functionality without sacrificing facile solution processability, making them promising candidates for multifunctional devices like dual EC/EL displays.

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“…[41][42][43][44] To further improve the performance of SM OSCs to meet commercial viability, it is highly desirable to unravel what makes the A-π -D-π -A structures special and how to tune the local packing morphology for efficient charge generation by side-chain engineering. These substituents are often detrimental to charge transport and can also influence the donor/acceptor (D/A) intermolecular arrangements.…”

Section: Doi: 101002/adts201800091mentioning

confidence: 99%

Rationalizing Small‐Molecule Donor Design toward High‐Performance Organic Solar Cells: Perspective from Molecular Architectures

Han

2018

Advcd Theory and Sims

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Tuning donor/acceptor interfacial arrangements and electron-transfer processes in the active layers is crucial to improve the performance of organic solar cells (OSCs). Here, the impact of different molecular architectures (i.e., A-π -D-π -A, D-π-A-π -D and π-A-D-A-π ) of the donors on the interfacial arrangements and electronic processes in small-molecule (SM) OSCs is elucidated by means of multiscale theoretical simulations. An A-π-D-π-A structured donor with sizable terminal units, extended π bridges, and bulky side groups on the backbone core is proved to be able to simultaneously obtain both efficient charge generation and migration as well as suppressed charge recombination, thus paving the way for the rational design of electron donors toward high-performance SM OSCs.Solution-processed bulk heterojunction (BHJ) organic solar cells (OSCs) have achieved remarkable progress in the past decade. [1][2][3][4][5][6][7][8][9] For fullerene-based small-molecule (SM) OSCs, power conversion efficiencies (PCEs) have exceeded 11%, which is in stark contrast to the highest value of 1% in 2006 (Figure 1a). [4,5,[10][11][12][13][14][15][16][17][18][19] This significant improvement is attributed to the great efforts in developing new SM donors and device optimizations. [20][21][22][23][24][25][26][27][28] To date, three typical push-pull molecular structures, namely, D-π -A-π -D, π -A-D-A-π , and A-π -D-π -A, have been successfully used as SM donors. It is noteworthy that most of the donors with PCEs over 9% are of A-π -D-π -A structures. [4,5,18,[29][30][31][32][33] Inspired by the success of fullerene-based SM OSCs, nonfullerene counterparts have shown faster progress in the past few years (Figure 1a). [8,9,[34][35][36][37] Similarly, for nonfullerene SM OSCs with PCEs over 9%, both the donors and acceptors adopt A-π -D-π -A and/or Aπ -A structures. [8,9,[38][39][40] To realize solution processing in organic solvents, alkyl side chains are necessary to attach to the

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Impact of the Nature of the Side‐Chains on the Polymer‐Fullerene Packing in the Mixed Regions of Bulk Heterojunction Solar Cells

Cited by 46 publications

References 34 publications

Modelling the morphology and thermomechanical behaviour of low-bandgap conjugated polymers and bulk heterojunction films

Modelling the morphology and thermomechanical behaviour of low-bandgap conjugated polymers and bulk heterojunction films

Multifunctional triphenylamine polymers synthesized via direct (hetero) arylation polymerization

Rationalizing Small‐Molecule Donor Design toward High‐Performance Organic Solar Cells: Perspective from Molecular Architectures

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