2,2′-Bis(1,3,4-thiadiazole)-Based π-Conjugated Copolymers for Organic Photovoltaics with Exceeding 8% and Its Molecular Weight Dependence of Device Performance

Fukuta, Seijiro; Seo, Jooyeok; Lee, Hoyeol; Kim, Hwajeong; Kim, Youngkyoo; Ree, Moonhor; Higashihara, Tomoya

doi:10.1021/acs.macromol.6b02475

Cited by 34 publications

(37 citation statements)

References 47 publications

(90 reference statements)

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“…The main absorption peaks of the thin polymers films redshifted and exhibited broader absorption peaks compared to those of the polymers in solution. This occurred because the chains of the thin fluorinated polymers films were likely to have been packed more closely compared to the polymers in solution, thus resulting in aggregation and enhanced intermolecular charge transfer (ICT) …”

Section: Methodsmentioning

confidence: 99%

A 3‐Fluoro‐4‐hexylthiophene‐Based Wide Bandgap Donor Polymer for 10.9% Efficiency Eco‐Friendly Nonfullerene Organic Solar Cells

Jeon

Choi

et al. 2019

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Nonfullerene organic solar cells (NFOSCs) are attracting increasing academic and industrial interest due to their potential uses for flexible and lightweight products using low‐cost roll‐to‐roll technology. In this work, two wide bandgap (WBG) polymers, namely P(fTh‐BDT)‐C6 and P(fTh‐2DBDT)‐C6, are designed and synthesized using benzodithiophene (BDT) derivatives. Good oxidation stability and high solubility are achieved by simultaneously introducing fluorine and alkyl chains to a single thiophene (Th) unit. Solid P(fTh‐2DBDT)‐C6 films present WBG optical absorption, suitable frontier orbital levels, and strong π–π stacking effects. In addition, P(fTh‐2DBDT)‐C6 exhibits good solubility in both halogenated and nonhalogenated solvents, suggesting its suitability as donor polymer for NFOSCs. The P(fTh‐2DBDT)‐C6:3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(5‐hexylthienyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene (ITIC‐Th) based device processed using chlorobenzene/1,8‐diiodooctane (CB/DIO) exhibits a remarkably high power conversion efficiency (PCE) of 11.1%. Moreover, P(fTh‐2DBDT)‐C6:ITIC‐Th reaches a high PCE of 10.9% when processed using eco‐friendly solvents, such as o‐xylene/diphenyl ether (DPE). The cell processed using CB/DIO maintains 100% efficiency after 1272 h, while that processed using o‐xylene/DPE presents a 101% increase in efficiency after 768 h and excellent long‐term stability. The results of this study demonstrate that simultaneous fluorination and alkylation are effective methods for designing donor polymers appropriate for high‐performance NFOSCs.

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Section: Methodsmentioning

confidence: 99%

A 3‐Fluoro‐4‐hexylthiophene‐Based Wide Bandgap Donor Polymer for 10.9% Efficiency Eco‐Friendly Nonfullerene Organic Solar Cells

Jeon

Choi

et al. 2019

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“…Therefore, the M n could be easily affected by synthetic condition such as polymerization time, temperature, concentration, and so on . In recent years, a lot of reported works have demonstrated that the M n usually has great impact on the performance of PSCs via significantly affecting the molecular orientation, hole mobility, domain purity, and vertical composition profiles . However, a systemic study that clarifies the dependence of optimal thickness of active layer on polymer M n , which is of vital importance to develop a facile approach to realize high‐performance thick‐film PSCs, has not been made.…”

Section: Introductionmentioning

confidence: 99%

Achieving an Efficiency Exceeding 10% for Fullerene‐based Polymer Solar Cells Employing a Thick Active Layer via Tuning Molecular Weight

Yang

Zhao

et al. 2017

Adv Funct Materials

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Recently, the influence of molecular weight (M n ) on the performance of polymer solar cells (PSCs) is widely investigated. However, the dependence of optimal thickness of active layer for PSCs on M n is not reported yet, which is vital to the solution printing technology. In this work, the effect of M n on the efficiency and especially optimal thickness of the active layer for PBTIBDTT-S-based PSCs is systematically studied. The device efficiency improves significantly as the M n increases from 12 to 38 kDa, and a remarkable efficiency of 10.1% is achieved, which is among the top efficiencies of wide-bandgap polymer:fullerene PSCs. Furthermore, the optimal thickness of the active layer is also greatly increased from 62 to 210 nm with increased M n . Therefore, a device employing a thick (>200 nm) active layer with power conversion efficiency exceeding 10% is achieved by manipulating M n . This exciting result is attributed to both the improved crystallinity, thus hole mobility, and preferable polymer orientation, thus morphology of active layer. These findings, for the first time, highlight the significant impact of M n on the optimal thickness of active layer for PSCs and provide a facile way to further improve the performance of PSCs employing a thick active layer.

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“…Thiazole derivatives, which contain sulfur and nitrogen atoms, have been considered as electron withdrawing unit candidates for conjugated polymers . Recently, a series of new π‐conjugated donor–acceptor alternating polymers based on various thiazole derivative units was reported; their synthesis and fundamental characterizations were discussed in detail. However, they were investigated in the aspect of only photoelectric performance as an active matrix component in solar cell devices.…”

Section: Molecular Weights and Polydispersity Indices Thermal Propermentioning

confidence: 99%

Nanoscale Film Morphology and n‐Type Digital Memory Characteristics of π‐Conjugated Donor–Acceptor Alternating Copolymer Based on Thiophene and Thiadiazole Units

Lee

Fukuta

Kim

et al. 2019

Macromol. Rapid Commun.

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Various molecular weight π‐conjugated donor–acceptor polymers based on thiadiazole and thiophene units are investigated with respect to nanoscale film morphology and digital memory performance. Interestingly, all polymers reveal excellent n‐type digital permanent memory characteristics, which are governed by the combination of Ohmic and trap‐limited space charge limited conductions via a hopping process using thiadiazole and thiophene units as charge traps and stepping stones. The digital memory performance is significantly influenced by the film morphology details that vary with the polymer molecular weight as well as the film thickness. A higher population of face‐on structure formation, as well as higher molecular weight, provides a wider film thickness window of digital memory operation. Overall, π‐conjugated PBTDzTV polymers are suitable for the production of high‐performance, programmable n‐type permanent memory devices with very low power consumption.

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2,2′-Bis(1,3,4-thiadiazole)-Based π-Conjugated Copolymers for Organic Photovoltaics with Exceeding 8% and Its Molecular Weight Dependence of Device Performance

Cited by 34 publications

References 47 publications

A 3‐Fluoro‐4‐hexylthiophene‐Based Wide Bandgap Donor Polymer for 10.9% Efficiency Eco‐Friendly Nonfullerene Organic Solar Cells

A 3‐Fluoro‐4‐hexylthiophene‐Based Wide Bandgap Donor Polymer for 10.9% Efficiency Eco‐Friendly Nonfullerene Organic Solar Cells

Achieving an Efficiency Exceeding 10% for Fullerene‐based Polymer Solar Cells Employing a Thick Active Layer via Tuning Molecular Weight

Nanoscale Film Morphology and n‐Type Digital Memory Characteristics of π‐Conjugated Donor–Acceptor Alternating Copolymer Based on Thiophene and Thiadiazole Units

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