Tuning fullerene miscibility with porphyrin-terminated P3HTs in bulk heterojunction blends

Seibers, Zach D.; Collier, Graham S.; Hopkins, Benjamin W.; Boone, Evan S.; Le, Thinh P.; Gomez, Enrique D.; Kilbey, S. Michael

doi:10.1039/d0sm01244k

Cited by 7 publications

(7 citation statements)

References 65 publications

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“…By adjusting the miscibility between donor and acceptor, the content of the blend phase can be adjusted. 72,[87][88][89][90][91][92][93][94][95] Miscibility is an intrinsic property of the material. Usually, good miscibility between the donor and acceptor would induce more content of intermixed phase.…”

Section: Regulating the Content Of Intermixed Phasementioning

confidence: 99%

Recent advances in intermixed phase of organic solar cells: Characterization, regulating strategies and device applications

Liang

Yao

et al. 2021

Journal of Polymer Science

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Organic solar cells (OSCs) have unique advantages of low-cost solution processing, light weight, flexibility, and semitransparency, which is a promising photovoltaic technology. The intermixed phase plays a key role in determining the power conversion efficiencies (PCE) of OSCs. The intermixed phase is an amorphous region, where the donor and acceptor mix at the molecular level.Great efforts have been devoted to optimize the content and the composition of the intermixed phase. This perspective focuses on the functions of intermixed phase and elaborates the relationship between intermixed phase behavior and photophysical process, in particular, the exciton dissociation and charge transport. Then the characterization methods, including quantitative and qualitative characterizations, for the content and composition of intermixed phases are introduced. Meanwhile, this review also introduces the strategies to control the intermixed phase behavior, such as adjusting the miscibility between donor and acceptor, changing the ratio of donor to acceptor, regulating the crystallinity and so on. Moreover, representative examples are given and discussed to understand the key parameters on tuning the intermixed phase behavior. Finally, a future controlling and development of intermixed phase behavior is briefly outlooked, which may help to achieve high PCE of OSCs.

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Section: Regulating the Content Of Intermixed Phasementioning

confidence: 99%

Recent advances in intermixed phase of organic solar cells: Characterization, regulating strategies and device applications

Liang

Yao

et al. 2021

Journal of Polymer Science

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“…Conjugated polymers (CPs) have been widely used in a variety of organic electronic devices including organic transistors, light-emitting diodes, solar cells, and sensors. − The performance of organic electronic devices is strongly dependent on the intermolecular morphologies of CPs such as translational and orientational orderings. − In particular, the liquid crystalline (LC) characteristics of CPs, arising from rod-like π-conjugated anisotropic shapes, have provided an effective way to achieve a long-range oriented molecular arrangement with effective charge transport. − These highly aligned self-assembled structures can be effectively obtained from the LC phase by reducing the energy barrier for crystal nucleation and coil-to-rod transitions during solution processing. − For example, LC characteristics have been reported in several CPs such as poly(2,5-bis(3-tetradecylthiophen-2yl)thieno(3,2- b )thiophene) (PBTTT), poly(3-hexylthiophene) (P3HT), and poly[3-(potassium-7-hexanoate)-thiophene-2,5-diyl] (P3PHT), significantly enhancing electrical performances by manipulating their LC structures. ,− Therefore, precise control of LC interaction, which determines the liquid crystalline behavior of rod-like polymers, has been considered crucial for achieving long-range ordering of CPs. However, it is still challenging and requires a fundamental understanding of the LC characteristics of the CPs. ,− …”

Section: Introductionmentioning

confidence: 99%

Regioregularity-Dependent Crystalline Structures and Thermal Transitions in Poly(3-dodecylthiophene)s

Park¹,

Han²,

Kim³

et al. 2021

Chem. Mater.

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The liquid crystalline (LC) characteristics of conjugated polymers (CPs) can result in their self-assembly with long-range ordering, providing an effective route for the formation of an optimized morphology suitable for high-performance organic electronic devices. In this study, the temperature-dependent LC phases of regioregularity (RR)-controlled poly(3-dodecylthiophene)s (P3DDTs) are systematically investigated. Controlling the RR of P3DDTs from 94 to 60% significantly modifies the strengths of their LC interactions, whereas their chemical structures remain almost the same. As the RR decreases, P3DDTs exhibit progressively decreased phase transition temperatures, i.e., the nematic-to-isotropic transition temperature, as measured using polarized optical microscopy (POM), UV–vis spectroscopy, differential scanning calorimetry (DSC), and X-ray scattering. P3DDTs with a high RR (94 and 83%) exhibit only the Form I crystal structures that are typically observed in most regioregular poly(3-alkylthiophene)s. However, P3DDTs with a low RR (76 and 60%) adopt both the Form I and Form II crystal structures, where Form II crystals contain interdigitated alkyl side-chain stackings. The amount of Form I crystals is significantly decreased as the RR decreases, and Form II crystals are dominantly observed for RR 60% P3DDT polymers. These features explain the significant decreases in the transition temperatures between the phases for P3DDTs with lower RR. This study provides an understanding of the RR effect in determining the crystalline structures and thermotropic LC behavior of P3DDTs, allowing for exquisite control over their self-assembly and optoelectrical properties.

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“…One method to stabilize device morphology is to add a compatibilizer as a third component into the active layer blend. , The compatibilizer localizes at the interface between immiscible phases, lowers the interfacial tension, and increases the interfacial adhesion. , Both small molecules − and polymers − have been used to stabilize domain sizes in active layer blends. In our previous work, we used a fullerene-functionalized P3HT copolymer to stabilize P3HT:PC 61 BM blend morphologies .…”

Section: Introductionmentioning

confidence: 99%

“…We found that a random copolymer with 20 mol % fullerene-functionalized side chains at 8 wt % in the blend was best at preventing micron-scale phase separation in annealed thin film blends and OPVs. In our work, and in other examples, 32,36,38,39,44 tailored compatibilizers were synthesized to match the specific donor and acceptor in the active layer of the OPV. Synthesizing custom compatibilizers is time-intensive and impractical for complex donor polymers.…”

Section: ■ Introductionmentioning

confidence: 99%

Fullerene-Functionalized Poly(3-hexylthiophene) Additive Stabilizes Conjugated Polymer–Fullerene Blend Morphologies

Kim

Mueller

Yang

et al. 2021

ACS Appl. Polym. Mater.

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Organic photovoltaics are again gaining traction as device power conversion efficiencies have increased substantially over the last two years. Despite these improved efficiencies, long-term device stability remains a challenge because the physical blend of an electron-donor and -acceptor in the active layer can phase-separate into larger domains over time. Copolymers that are miscible with both the donor and acceptor can stabilize the active layer blend morphology, but these additives are often tailored to match the specific donor/acceptor blend. We demonstrate herein that a single copolymer containing a conjugated poly(3-hexylthiophene) backbone and fullerene-functionalized side chains serves as a general blend stabilizer. Optical microscopy revealed that phase separation was suppressed in three different conjugated polymer/fullerene blends (PTB7, PTB7-Th, and PffBT4T-2OD with PC71BM) when annealed with the copolymer in thin films. Moreover, phase separation was suppressed in photovoltaic devices containing PffBT4T-2OD:PC71BM with the copolymer in the active layer. We also investigated factors beyond morphology that affect the initial power conversion efficiency, which was lower for devices with the copolymer. Overall, our results demonstrate that a single fullerene-functionalized poly(3-hexylthiophene) copolymer additive suppresses phase separation in multiple conjugated polymer/fullerene thin film blends as well as in a photovoltaic device.

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Tuning fullerene miscibility with porphyrin-terminated P3HTs in bulk heterojunction blends

Abstract: Porphyrin-terminated P3HTs represent an example of molecular engineering, where π-stacking interactions with the porphyrin enhance fullerene miscibility in BHJ blends.

Cited by 7 publications

References 65 publications

Recent advances in intermixed phase of organic solar cells: Characterization, regulating strategies and device applications

Recent advances in intermixed phase of organic solar cells: Characterization, regulating strategies and device applications

Regioregularity-Dependent Crystalline Structures and Thermal Transitions in Poly(3-dodecylthiophene)s

Fullerene-Functionalized Poly(3-hexylthiophene) Additive Stabilizes Conjugated Polymer–Fullerene Blend Morphologies

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