Diketopyrrolopyrrole‐based Conjugated Polymers Bearing Branched Oligo(Ethylene Glycol) Side Chains for Photovoltaic Devices

Chen, Xingxing; Zhang, Zijian; Ding, Zicheng; Li, Jun; Wang, Lixiang

doi:10.1002/anie.201602775

Cited by 130 publications

(116 citation statements)

References 43 publications

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“…Our results are in agreement with previous reports that have shown that replacement of solubilizing chains can increase the dielectric constant . However, work done examining the effect of the increase of the dielectric constant via solubilizing chain modifications have shown that increase in performance only corresponds to changes in morphology, not the increased dielectric constant . The synthesis of TEG‐DPP‐BF is reported in the Experimental Section.…”

Section: Resultsmentioning

confidence: 99%

Determining the Dielectric Constants of Organic Photovoltaic Materials Using Impedance Spectroscopy

Hughes

Rosenthal

Ran

et al. 2018

Adv Funct Materials

109

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The photovoltaic and electrical properties of organic semiconductors are characterized by their low dielectric constant, which leads to the formation of polarons and Frenkel excitons. The low dielectric constant of organic semiconductors has been suggested to be significantly influential in geminate and bimolecular recombination losses in organic photovoltaics (OPVs). However, despite the critical attention that the dielectric constant has received in literature discussions, there has not yet been a thorough study of the dielectric constant in common organic semiconductors and how it changes when blended. In fact, there have been some inconsistent and contradictory reports on such dielectric constants, making it difficult to identify trends. Herein, at first a detailed explanation of a specific methodo logy to determine the dielectric constant in OPV materials with impedance spectroscopy is provided, including guidelines for possible experimental pitfalls. Using this methodology, the analysis for the dielectric constant of 17 common neat organic semiconductors is carried out. Furthermore, the relationship between the dielectric constant and blend morphology are studied and determined. It is found that the dielectric constant of a blend system can be very accurately predicted solely based on the dielectric con stants of the neat materials, scaled by their respective weight ratios in the blend film.

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Section: Resultsmentioning

confidence: 99%

Determining the Dielectric Constants of Organic Photovoltaic Materials Using Impedance Spectroscopy

Hughes

Rosenthal

Ran

et al. 2018

Adv Funct Materials

109

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show abstract

“…While Donaghey et al reported nonfullerene acceptors with remarkably high dielectric constants up to 9.8 by adding oligo(ethylene oxide) chains to the backbones, no device performance was reported . In addition, oligo(ethylene oxide) chains have been attached to donor polymers, leading to an increase of dielectric constant from 2 or 3 for the polymers with alkyl side chains to ≈5 . Lu and Yang separately investigated polymers with fluorine atoms attached to polymer backbones and observed an increase in dielectric constant with fluorine substituents and an improvement in device PCE .…”

Section: Introductionmentioning

confidence: 99%

Donor Conjugated Polymers with Polar Side Chain Groups: The Role of Dielectric Constant and Energetic Disorder on Photovoltaic Performance

Huang

et al. 2018

Adv Funct Materials

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To better understand the correlation of the dielectric properties with the photovoltaic response in conjugated polymer:fullerene bulk heterojunction materials, the concept of introducing minimal structural change is employed to increase the polymer dielectric constant via polar cyano groups added to the end of butyl or octyl side chains in the poly(dithienosilole-thienopyrrolodione) system. Density functional theory calculations confirm that the polar groups do not affect the polymer electronic structure but can lead to an increase in overall dipole moment depending on the polymer chain conformation. Despite the increased dielectric constant (from 2.7 to 4.3 for cyano-octyl side chains and from 2.7 to 3.2 for the cyano-butyl analogues), the device characteristics employing the cyano-containing polymers are inferior to those of the devices made with unfunctionalized alkyl chains. It is found that the hole mobilities for the cyano-containing polymers are two orders of magnitude lower compared to those for the parent polymers and suggest this is due to an increase in energetic disorder caused by the strong local permanent dipoles associated with the cyano groups. The study highlights the complexity in the relationship between the dielectric constant of organic materials, the morphologies that are induced, and their photovoltaic performance.

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“…[20][21][22][23][24][25][26] Fullerene derivatives were regarded as a promising electronic transport layer (ETL) material due to their distinguished advantages of high electron mobility and good energy level matching with the active layers of OSCs. [27][28][29][30][31] The polarities of the fullerene derivatives were influenced significantly by the presence of functional groups, such as sulfonate, ether chain, ester, and carboxylic acid [32][33][34][35] A few fullerene derivatives with functionalized anchoring groups have been developed as a modification layer of metal oxide in inverted OSCs. [36][37][38] They can be easily processed through a solution-based method, which demonstrated good compatibility between organic active layer and metal oxide.…”

Section: Doi: 101002/macp201800477mentioning

confidence: 99%

Synthesis and Application of Functionalized Diblock Amphiphilic Fullerene Derivatives

Liu

et al. 2019

Macro Chemistry & Physics

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A series of functionalized amphiphilic diblock fullerene derivatives C60‐4TPB, C60‐2DPE, C60‐4HTPB, C60‐PHFBS, and C60‐2BEFPE are developed and applied as the modification layers on zinc oxide (ZnO) in inverted organic solar cell (OSC) devices. By spin‐coating ZnO, the fullerene derivatives layer can reduce the work function of ZnO via modulation of the interfacial dipoles. When introducing solvent treatment by toluene during the preparation of films, the order of the fullerene derivatives layer are clearly increased, which are supported by X‐ray diffraction and contact angle of water measurements. The OSCs devices modified with those fullerene derivatives show power conversion efficiency of 8.62%, 9.21%, 8.86%, 9.14%, and 9.15% based on poly‐[4,8‐bis(5‐(2‐ethylhexyl)‐thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]‐dithiophene‐alt‐3‐fluoro thieno‐[3,4‐b] thiophene‐2‐carboxylate] (PTB7‐Th) and [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM) blend, respectively. All the results indicate that the development of diblock amphiphilic fullerene derivatives opens a new opportunity to modify the present defects of ZnO by simultaneously modulating interfacial work functions, the wetting properties of the interlayer, and the active layer.

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Diketopyrrolopyrrole‐based Conjugated Polymers Bearing Branched Oligo(Ethylene Glycol) Side Chains for Photovoltaic Devices

Cited by 130 publications

References 43 publications

Determining the Dielectric Constants of Organic Photovoltaic Materials Using Impedance Spectroscopy

Determining the Dielectric Constants of Organic Photovoltaic Materials Using Impedance Spectroscopy

Donor Conjugated Polymers with Polar Side Chain Groups: The Role of Dielectric Constant and Energetic Disorder on Photovoltaic Performance

Synthesis and Application of Functionalized Diblock Amphiphilic Fullerene Derivatives

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