Azadipyrromethene‐Based Zn(II) Complexes as Nonplanar Conjugated Electron Acceptors for Organic Photovoltaics

Mao, Zhenghao; Senevirathna, Wasana; Liao, Jiayu; Gu, Jun; Kesava, Sameer Vajjala; Guo, Changhe; Gomez, Enrique D.; Sauvé, Geneviève

doi:10.1002/adma.201400647

Cited by 95 publications

(102 citation statements)

References 29 publications

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“…We have shown that derivatives of Zn(ADP) 2 are promising electron acceptors for organic photovoltaics (OPVs) [9–10]. A series of zinc(II) derivatives with various pyrrolic substitutions showed power conversion efficiencies (PCEs) ranging from 2.2–4.1% when blended with poly(3-hexylthiophene) (P3HT), and the highest PCE was obtained with Zn(WS3) 2 , shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…A series of zinc(II) derivatives with various pyrrolic substitutions showed power conversion efficiencies (PCEs) ranging from 2.2–4.1% when blended with poly(3-hexylthiophene) (P3HT), and the highest PCE was obtained with Zn(WS3) 2 , shown in Fig. 1 [9–10]. In comparison, free ligands and BF 2 + chelates showed negligible power conversion efficiencies, and Zn(ADP) 2 gave a maximum efficiency of 1.4% [11].…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

Etheridge¹,

Fernando²,

Pejić³

et al. 2016

Beilstein J. Org. Chem.

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SummaryHomoleptic zinc(II) complexes of di(phenylacetylene)azadipyrromethene (e.g., Zn(WS3)2) are potential non-fullerene electron acceptors for organic photovoltaics. To tune their properties, fluorination of Zn(WS3)2 at various positions was investigated. Three fluorinated azadipyrromethene-based ligands were synthesized with fluorine at the para-position of the proximal and distal phenyl groups, and at the pyrrolic phenylacetylene moieties. Additionally, a CF3 moiety was added to the pyrrolic phenyl positions to study the effects of a stronger electron withdrawing unit at that position. The four ligands were chelated with zinc(II) and BF2 + and the optical and electrochemical properties were studied. Fluorination had little effect on the optical properties of both the zinc(II) and BF2 + complexes, with λmax in solution around 755 nm and 785 nm, and high molar absorptivities of 100 × 103 M−1cm−1 and 50 × 103 M−1cm−1, respectively. Fluorination of Zn(WS3)2 raised the oxidation potentials by 0.04 V to 0.10 V, and the reduction potentials by 0.01 V to 0.10 V, depending on the position and type of substitution. The largest change was observed for fluorine substitution at the proximal phenyl groups and CF3 substitution at the pyrrolic phenylacetylene moieties. The later complexes are expected to be stronger electron acceptors than Zn(WS3)2, and may enable charge transfer from other conjugated polymer donors that have lower energy levels than poly(3-hexylthiophene) (P3HT).

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

Etheridge¹,

Fernando²,

Pejić³

et al. 2016

Beilstein J. Org. Chem.

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“…Compared with fullerene acceptors, nonfullerene acceptors present some advantages, such as broad and strong absorption, adjustable LUMO energy levels, and long‐term stability. In recent years, FF‐OSCs developed quickly21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42 and achieved PCEs of up to 6.8% 25…”

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confidence: 99%

Roll‐Coated Fabrication of Fullerene‐Free Organic Solar Cells with Improved Stability

et al. 2015

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“…In recent years, there has been signi-cant advancement in small-molecule-based non-fullerene acceptors for OSCs. [37][38][39][40][41][42][43][44][45] We note that our objective in this work is to investigate the impact of small structural differences on device performance, rather than to achieve the state-of-art PCE. Before an OSC device was fabricated, uorescence quenching experiments were conducted to determine the optimum ratio between P3HT and BTD-P compounds.…”

Section: Application To Organic Solar Cell As Electron Acceptorsmentioning

confidence: 99%

Theory guided systematic molecular design of benzothiadiazole–phenazine based self-assembling electron-acceptors

et al. 2017

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We report two new self-assembling n-type materials in which the design process was systematically analyzed using theoretical calculations prior to experimental synthesis. Benzothiadiazole (A 0 ) and alkoxyphenazine (A) serve as our basic electron-deficient building blocks to construct two candidate molecules with an acceptor (A) -acceptor (A 0 ) -acceptor (A) configuration. We conducted a computational characterization (B3LYP/6-31G*) of the electronic properties for structural subunits linked together and analyzed in a step-by-step fashion, thereby culminating in the target molecules of interest. We found that E LUMO was controlled primarily by benzothiadiazole as was evident by orbital localization on this subunit. Meanwhile, E HOMO was influenced by the dihedral angle between A and A 0 .The molecule with A and A 0 coupled with a C-C triple bond (BTD-P-T) was found to be planar with a more stabilized E LUMO and a reduced E gap when compared to its C-C single bond counterpart (BTD-P-S). The two molecules were synthesized and characterized to verify the theoretical findings. Optical, electrochemical, and thermal properties were characterized with UV-vis absorption and fluorescence spectroscopy, cyclic voltammetry, and differential scanning calorimetry, respectively. In addition, the molecular packing was examined by X-ray powder diffraction. As predicted by theory, BTD-P-T exhibited a lower E gap based on the system's lower E LUMO in comparison to BTD-P-S. BTD-P-T exhibited a higher T m and crystallinity due to its planarity. Both BTD-P-S and BTD-P-T exhibited excellent fibrillation ability upon solvent casting. Bulk heterojunction (BHJ) organic solar cell (OSC) devices were fabricated using BTD-P-S or BTD-P-T as an acceptor and P3HT as a donor at different weight ratios. For both P3HT:BTD-P-S and P3HT:BTD-P-T BHJs, the weight ratio of 6 : 1 produced the highest power conversion efficiency (PCE) of 0.17% and 0.44%, respectively. These results are consistent with fluorescence quenching experiments in which 90% of P3HT fluorescence was quenched at that ratio.Nearly two times higher PCE was observed for the BTD-P-T based device compared to that of the BTD-P-S based system, mainly due to the higher J sc . Presumably, the flat geometry of BTD-P-T allows for more efficient intermolecular p-orbital overlap, enhancing charge transport.

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Azadipyrromethene‐Based Zn(II) Complexes as Nonplanar Conjugated Electron Acceptors for Organic Photovoltaics

Cited by 95 publications

References 29 publications

Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

Roll‐Coated Fabrication of Fullerene‐Free Organic Solar Cells with Improved Stability

Theory guided systematic molecular design of benzothiadiazole–phenazine based self-assembling electron-acceptors

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