Semi-paracrystallinity in semi-conducting polymers

Marina, Sara; Gutiérrez, Edgar; Gutierrez, Junkal; Gobbi, Marco; Ramos, Nicolás; Solano, Eduardo; Rech, Jeromy James; You, Wei; Hueso, Luis E.; Tercjak, Agnieszka; Ade, Harald; Martı́n, Jaime San

doi:10.1039/d1mh01349a

Cited by 22 publications

(24 citation statements)

References 35 publications

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“…19 The solution processing of P(NDI2OD-T2) (such as via spin coating) produces thin films with semicrystalline (or "semi-paracrystalline") microstructure facilitated by the self-organization of polymer chains as the film dries. 21 T2), form I and form II, have been observed. 22 Form I packing is characterized by a segregated packing of the NDI and T2 units in separated columns along the π−π stacking direction, which is observed in as-cast films and those annealed at mild annealing temperatures.…”

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confidence: 91%

Third Crystalline Form of P(NDI2OD-T2) with Pronounced End-on Texture

Đoán

Tan

et al. 2023

ACS Macro Lett.

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We report the observation of a third crystalline polymorph, “form III”, of the well-studied electron-transporting conjugated polymer P(NDI2OD-T2) that exhibits end-on texture. This third polymorph of P(NDI2OD-T2) is distinguished from other polymorphs by having two monomer units incorporated along the backbone-stacking direction, resulting in a doubling of the c axis of the unit cell. Form III crystallites are realized by melt-annealing a thin film followed by slow cooling. The distinct packing of this third polymorph is established through the application of grazing-incidence wide-angle X-ray scattering (GIWAXS) measurements combined with peak simulation of candidate unit cells. The discovery of a third polymorph of P(NDI2OD-T2) provides a fresh opportunity for studying structure/function relationships of this important semiconducting polymer.

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confidence: 91%

Third Crystalline Form of P(NDI2OD-T2) with Pronounced End-on Texture

Đoán

Tan

et al. 2023

ACS Macro Lett.

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“…Among these, one of the most important questions is how preexisting molecular order in the liquid state impacts crystallization and solid-state microstructure development. Due to the rigidity of aromatic backbones and their amphiphilic nature, many high-performing, crystallizable semiconducting polymers exhibit liquid-crystalline behavior; therefore, crystallization in these polymers likely occurs via the stacking of polymer chain segments that exhibit a preexisting order in the liquid state. − Moreover, even nonliquid-crystalline polymer semiconductors are known to exhibit a strong tendency to form aggregates with local molecular order prior to crystallization. − Therefore, a major fundamental question in the field remains as to whether or not (and if so, how) the crystallization process of semiconducting polymers is affected by the presence of molecular order in the liquid state.…”

Section: Introductionmentioning

confidence: 99%

Unraveling the Influence of the Preexisting Molecular Order on the Crystallization of Semiconducting Semicrystalline Poly(9,9-di-n-octylfluorenyl-2,7-diyl (PFO)

et al. 2022

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Understanding the complex crystallization process of semiconducting polymers is key for the advance of organic electronic technologies as the optoelectronic properties of these materials are intimately connected to their solid-state microstructure. These polymers often have semirigid backbones and flexible side chains, which results in a strong tendency to organize/ order in the liquid state. Therefore, crystallization of these materials frequently occurs from liquid states that exhibit�at least partial� molecular order. However, the impact of the preexisting molecular order on the crystallization process of semiconducting polymers� indeed, of any polymer�remained hitherto unknown. This study uses fast scanning calorimetry (FSC) to probe the crystallization kinetics of poly(9,9-di-n-octylfluorenyl-2,7-diyl (PFO) from both an isotropic disordered melt state (ISO state) and a liquidcrystalline ordered state (NEM state). Our results demonstrate that the preexisting molecular order has a profound impact on the crystallization of PFO. More specifically, it favors the formation of effective crystal nucleation centers, speeding up the crystallization kinetics at the early stages of phase transformation. However, samples crystallized from the NEM state require longer times to reach full crystallization (during the secondary crystallization stage) compared to those crystallized from the ISO state, likely suggesting that the preexisting molecular order slows down the advance in the latest stages of the crystallization, that is, those governed by molecular diffusion. The fitting of the data with the Avrami model reveals different crystallization mechanisms, which ultimately result in a distinct semicrystalline morphology and photoluminescence properties. Therefore, this work highlights the importance of understanding the interrelationships between processing, structure, and properties of polymer semiconductors and opens the door for performing fundamental investigations via newly developed FSC methodologies of such materials that otherwise are not possible with conventional techniques.

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“…PBDBT is a rigid semi‐conducting polymer with complex morphology which has been variously characterized as crystalline, [ 53 , 54 ] amorphous, [ 55 ] and most recently as semi‐paracrystalline. [ 56 ] PBDBT‐PCBM devices showed an increase in PCE from 7.1% to 7.8% upon incorporation of a 5 wt% loading of MONs. This was accompanied by an underlying increase in J SC by 1 mA cm −2 and FF by 1% with no change in V OC .…”

Section: Resultsmentioning

confidence: 99%

Metal‐Organic Framework Nanosheets as Templates to Enhance Performance in Semi‐Crystalline Organic Photovoltaic Cells

et al. 2022

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Optimizing the orientation, crystallinity, and domain size of components within organic photovoltaic (OPV) devices is key to maximizing their performance. Here a broadly applicable approach for enhancing the morphology of bulk heterojunction OPV devices using metal-organic nanosheets (MONs) as additives is demonstrated. It is shown that addition of porphyrin-based MONs to devices with fully amorphous donor polymers lead to small improvements in performance attributed to increased light absorption due to nanosheets. However, devices based on semi-crystalline polymers show remarkable improvements in power conversion efficiency (PCE), more than doubling in some cases compared to reference devices without nanosheets. In particular, this approach led to the development of PffBT4T2OD-MON-PCBM device with a PCE of 12.3%, which to the authors' knowledge is the highest performing fullerene based OPV device reported in literature to date. Detailed analysis of these devices shows that the presence of the nanosheets results in a higher fraction of face-on oriented polymer crystals in the films. These results therefore demonstrate the potential of this highly tunable class of two-dimensional nanomaterials as additives for enhancing the morphology, and therefore performance, of semi-crystalline organic electronic devices.

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Semi-paracrystallinity in semi-conducting polymers

Abstract: Precise determination of structural organization of semi-conducting polymers is of paramount importance for the further development of these materials in organic electronic technologies. Yet, prior characterization of some of the...

Cited by 22 publications

References 35 publications

Third Crystalline Form of P(NDI2OD-T2) with Pronounced End-on Texture

Third Crystalline Form of P(NDI2OD-T2) with Pronounced End-on Texture

Unraveling the Influence of the Preexisting Molecular Order on the Crystallization of Semiconducting Semicrystalline Poly(9,9-di-n-octylfluorenyl-2,7-diyl (PFO)

Metal‐Organic Framework Nanosheets as Templates to Enhance Performance in Semi‐Crystalline Organic Photovoltaic Cells

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