Engineering dielectric constants in organic semiconductors

Armin, Ardalan; Stoltzfus, Dani M.; Donaghey, Jenny E.; Clulow, Andrew J.; Nagiri, Ravi Chandra Raju; Burn, Paul L.; Gentle, Ian R.; Meredith, Paul

doi:10.1039/c7tc00893g

Cited by 62 publications

(77 citation statements)

References 33 publications

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“…[18,19] Introducing highly polar groups to increase ε r in conjugated polymers has been an approach favored by some research groups. [7,10,13,[20][21][22] Such efforts have mainly focused on the introduction of the polar groups within the side chains to avoid disturbing the conjugated backbone, and although ε r increased, the subsequent performance in an OPV was variable, quite likely due to the influence of such polar groups on blend micro structure. An alternative approach has been the blending of higher dielectric additives with the active layer.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Backbone Fluorination on the Dielectric Constant of Conjugated Polythiophenes

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Bovo

Occhi

et al. 2017

Adv Elect Materials

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The ability to modify or enhance the dielectric constant of semiconducting polymers can prove valuable for a range of optoelectronic and microelectronic applications. In the case of organic photovoltaics, increasing the dielectric constant of the active layer has often been suggested as a method to control charge generation, recombination dynamics, and ultimately, the power conversion efficiencies. In this contribution, the impact that the degree and pattern of fluorination has on the dielectric constant of poly(3‐octylthiophene) (P3OT), a more soluble analogue of the widely studied conjugated material poly(3‐hexylthiophene), is explored. P3OT and its backbone‐fluorinated analogue, F‐P3OT, are compared along with a block and alternating copolymer version of these materials. It is found that the dielectric constant of the polymer thin films increases as the degree of backbone fluorination increases, in a trend consistent with density functional theory calculations of the dipole moment.

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Section: Introductionmentioning

confidence: 99%

The Influence of Backbone Fluorination on the Dielectric Constant of Conjugated Polythiophenes

Boufflet

Bovo

Occhi

et al. 2017

Adv Elect Materials

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“…The electron mobility increased by an order of magnitude in diodes. They later synthesized a dimer and polymer of K12 with OEG side chains and observed similar mobility improvements . They also reported optical high frequency ϵ r of 4.6 and 4.2 for the dimer and polymer, respectively.…”

Section: Trends/directionsmentioning

confidence: 76%

Designing Alternative Non‐Fullerene Molecular Electron Acceptors for Solution‐Processable Organic Photovoltaics

Sauvé

2019

The Chemical Record

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Until recently, solution‐processable organic photovoltaics (OPVs) mainly relied on fullerene derivatives as the n‐type material, paired with a p‐type conjugated polymer. However, fullerene derivatives have disadvantages that limit OPV performance, thus fueling research of non‐fullerene acceptors (NFAs). Initially, NFAs showed poor performance due to difficulties in obtaining favorable blend morphologies. One example is our work with 2,6‐dialkylamino core‐substituted naphthalene diimides. Researchers then learned to control blend morphology by NFA molecular design. To limit miscibility with polymer while preventing excessive self‐aggregation, non‐planar, twisted or 3D structures were reported. An example of a 3D structure is our work with homoleptic zinc(II) complexes of azadipyrromethene. The most recent design is a planar A‐D‐A conjugated system where the D unit is rigid and has orthogonal side chains to control aggregation. These have propelled power conversion efficiencies (PCEs) to ∼14 %, surpassing fullerene‐based OPVs. These exciting new developments prompt further investigations of NFAs and provide a bright future for OPVs.

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“…The dielectric constant (ε r ) of the material is another factor which governs the various loss processes inherently associated with the solar cells. Higher value of ε r leads to the reduction in the charge recombinations which in turn improves the charge carrier extraction efficiency , , . Therefore we set out to measure dielectric constant for our system at different frequencies ranging from 100–10 5 Hz (Figure S30).…”

Section: Resultsmentioning

confidence: 99%

Accepting to Donate: NDI‐Based Small Molecule as a Donor for Bulk Heterojunction Binary Solar Cells

et al. 2020

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A small molecular D‐π‐A‐π‐D triad NDIP consisting of naphthalenediimide (NDI) as an acceptor and porphyrin as a donor was synthesized. NDIP exhibits an intense absorption from visible to NIR region (400 nm to 1000 nm) with high molecular extinction coefficient. Endowed with excellent absorption and good charge carrier mobility, the molecule was used as a donor, against the normal perception as an acceptor due to the electron‐deficient nature of NDI, in the binary bulk heterojunction solar cells with PCBM as an acceptor. The cell demonstrated remarkable power conversion efficiency of 8.45 % with extremely low Eloss of 0.40 eV, which is also the best recorded for NDI based small molecule organic solar cells.

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Engineering dielectric constants in organic semiconductors

Abstract: An optical-frequency dielectric constant of 4.6 leads to improved charge generation efficiency in an organic semiconductor homojunction photovoltaic device.

Cited by 62 publications

References 33 publications

The Influence of Backbone Fluorination on the Dielectric Constant of Conjugated Polythiophenes

The Influence of Backbone Fluorination on the Dielectric Constant of Conjugated Polythiophenes

Designing Alternative Non‐Fullerene Molecular Electron Acceptors for Solution‐Processable Organic Photovoltaics

Accepting to Donate: NDI‐Based Small Molecule as a Donor for Bulk Heterojunction Binary Solar Cells

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