Axially phenoxylated aluminum phthalocyanines and their application in organic photovoltaic cells

Raboui, Hasan; AL-Amar, Mohammad; Abdelrahman, Ahmed I.; Bender, Timothy P.

doi:10.1039/c5ra04919a

Cited by 13 publications

(16 citation statements)

References 69 publications

(102 reference statements)

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“…The V OC s are higher than those based on literature-Cl-Cl n BsubNc and are consistent with a steric shielding effect, 40 observed with sterically bulky groups (i.e. phenoxy groups) in small molecule- 41−43 and polymer 44 -based OPVs. This effect is explained by an increase in the distance between the donor and acceptor materials induced by steric hindrance.…”

Section: Resultssupporting

confidence: 83%

Phenoxy-(Chloro)_n-Boron Subnaphthalocyanines: Alloyed Mixture, Electron-Accepting Functionality, and Enhanced Solubility for Bulk Heterojunction Organic Photovoltaics

et al. 2018

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The first set of phenoxy BsubNc compounds, PhO-Cl n BsubNc and F 5 -Cl n BsubNc, was synthesized through an axial displacement reaction of Cl-Cl n BsubNc with phenol and pentafluorophenol (respectively). Like their precursor, the products were found to be an alloyed mixture of phenoxylated Cl n BsubNcs with random positioning in the solid state yet consistent frequency of bay position chlorination. The average bay position chlorine occupancy was determined to be 0.99 through single crystal diffraction of PhO-Cl n BsubNc. Although the phenoxylation of Cl-Cl n BsubNc did not influence the chromophore photophysical properties, the electrochemical behavior was found to be more stable. Phenoxylation yielded differences in organic photovoltaic (OPV) device metrics. Specifically, a significant increase in open circuit voltage ( V OC ) was observed, ultimately exceeding 1.0 V when phenoxylated Cl n BsubNcs were paired with alpha-sexithiophene (α-6T) in planar heterojunction OPVs. Phenoxylation enabled the first example of BsubNcs incorporated into polymer-based bulk heterojunction (BHJ) OPVs through enhanced solubility. Phenoxylated Cl n BsubNcs, when paired with poly-3-hexylthiophene, also showed high V OC in BHJ OPVs with broad spectral absorption up to 760 nm. In the BHJ case, simple phenoxy was shown to be a better axial substituent compared to pentafluorophenoxy. This study represents the first example of using Cl n BsubNcs with nonchlorine axial substituents in OPVs and demonstrates that phenoxylation has a significant impact on device metrics while enhancing solubility to enable incorporation of Cl n BsubNcs into BHJ OPVs.

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Section: Resultssupporting

confidence: 83%

Phenoxy-(Chloro)_n-Boron Subnaphthalocyanines: Alloyed Mixture, Electron-Accepting Functionality, and Enhanced Solubility for Bulk Heterojunction Organic Photovoltaics

et al. 2018

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“…We had previously developed a simple thermodynamic model to examine and predict the spontaneity of the phenoxylation reaction of multiple chloro Pc derivatives. 40 Here, we developed a similar thermodynamic model for the halide exchange reaction for the chloro/dichloro MPcs of interest, using different cesium halide salts (i.e., CsF, CsBr, and CsI, eq 1). The model enables the consideration of a thermodynamic driving force for the halide exchange alongside solubility considerations.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Straightforward and Relatively Safe Process for the Fluoride Exchange of Trivalent and Tetravalent Group 13 and 14 Phthalocyanines

et al. 2019

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To avoid the use of hydrofluoric acid, a series of fluorinated trivalent and tetravalent metal-containing phthalocyanines (MPcs) were synthesized using a straightforward one-step halide substitution process using cesium fluoride (CsF) as the fluoride source and by reflux in N , N -dimethylformamide for less than an hour. The resulting fluoro MPcs were characterized and compared to the parent chloro MPcs. In some cases, very little change in properties was observed between the fluoro MPcs and the chloro MPcs. In other cases, such as fluoro aluminum phthalocyanine, a blue shift in the absorbance characteristics and an increase in oxidation and reduction potential of as much as 0.22 V was observed compared to the chloro derivative. Thermo gravimetric analysis was performed on all halo-MPcs, indicating that the choice of halo substitution on the axial position can have an effect on the decomposition or sublimation temperature of the final compound. After initial establishment and characterization of the fluoro MPcs, the halide substitution reaction of difluoro silicon phthalocyanine (F 2 -SiPc) was further explored by scaling the reaction up to a gram scale as well as considering tetrabutylammonium fluoride (TBAF) as an additional safe fluoride source. The scaled-up reactions producing F 2 -SiPc using CsF and TBAF as fluoride exchange sources were successfully reproducible, resulting in reaction yields of 100 and 73%, respectively. Both processes led to pure final products but results indicate that CsF, as the fluoride exchange reagent, appears to be the superior reaction process as it has a much higher yield.

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“…Surprisingly, none of the studied perfluorophthalocyanines showed detachment of the axial chlorine functionality within the temperature regime applied. It was reported previously that phthalocyanines with three‐valent metals and axial substituents (e.g., NO 2 PhO, F 5 PhO) tend to lose the axial functionalities upon heating …”

Section: Resultsmentioning

confidence: 99%

“…It was reported previously that phthalocyanines with three-valent metals and axial substituents (e.g.,N O 2 PhO, F 5 PhO) tend to lose the axial functionalities upon heating. [21] Because the perfluorophthalocyaninesi nvestigated tend to sublime at ar elatively low temperature we were unable to capturethe exact temperatures at which 4-6 thermally decompose or melt. Thisl ed to the conclusion that 4-6 are perfect candidates for the formation of evaporated thin films and the fabrication of dye-based optoelectronic devices.M oreover, these experimentsh ighlighted the fact that perfluorination of the indium,g allium,a nd aluminium phthalocyanines increases their vapor pressure despite the relatively high molecular masses of thesem olecules (ca.…”

Section: Thermogravimetric Analysismentioning

confidence: 99%

Highly Thermostable, Non‐oxidizable Indium, Gallium, and Aluminium Perfluorophthalocyanines with n‐Type Character

Łapok

Obłoza

Nowakowska

2016

Chemistry A European J

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Perfluorophthalocyanines incorporating three-valent metals, namely In(Cl), Ga(Cl), and Al(Cl), have been synthesized and characterized. Thermogravimetric analysis revealed that these compounds exhibit outstanding thermal stability and a tendency to sublime at a temperature exceeding around 350 °C without thermal decomposition. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to probe the frontier orbital energy levels of these compounds in THF solution. All three compounds undergo three quasi-reversible reductions with the first one leading to the formation of an anion radical, namely MPc(-.) , as confirmed by spectroelectrochemistry. The compounds studied were intrinsically resistive to oxidation, which indicates that they are very good electron acceptors (n-type materials). The HOMO-LUMO energy gaps (Eg ) of the three compounds determined by UV/Vis spectroscopy were relatively unaffected by the three-valent metals incorporated into the phthalocyanine macrocycle. Similarly, the energies of the HOMO (EHOMO ) and LUMO (ELUMO ) orbitals remained virtually unaffected by the three-valent metals in the perfluorophthalocyanine. Importantly, all the perfluorophthalocyanines studied possess LUMO levels between -4.76 and -4.85 eV, which makes their reduced forms resistant to electron trapping by O2 and H2 O. This property opens up the possibility for the fabrication of electronic devices operating under ambient conditions. All three compounds demonstrated very good photostability as solid thin films.

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Axially phenoxylated aluminum phthalocyanines and their application in organic photovoltaic cells

Abstract: Phenoxylation of chloro aluminum phthalocyanine (Cl-AlPc) can be easily achieved only when using “acidic phenols”. Once incorporated into unoptimized organic photovoltaics (OPVs) the result is an increase in the VOC.

Cited by 13 publications

References 69 publications

Phenoxy-(Chloro)_n-Boron Subnaphthalocyanines: Alloyed Mixture, Electron-Accepting Functionality, and Enhanced Solubility for Bulk Heterojunction Organic Photovoltaics

Phenoxy-(Chloro)_n-Boron Subnaphthalocyanines: Alloyed Mixture, Electron-Accepting Functionality, and Enhanced Solubility for Bulk Heterojunction Organic Photovoltaics

Straightforward and Relatively Safe Process for the Fluoride Exchange of Trivalent and Tetravalent Group 13 and 14 Phthalocyanines

Highly Thermostable, Non‐oxidizable Indium, Gallium, and Aluminium Perfluorophthalocyanines with n‐Type Character

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Axially phenoxylated aluminum phthalocyanines and their application in organic photovoltaic cells

Abstract: Phenoxylation of chloro aluminum phthalocyanine (Cl-AlPc) can be easily achieved only when using “acidic phenols”. Once incorporated into unoptimized organic photovoltaics (OPVs) the result is an increase in the VOC.

Cited by 13 publications

References 69 publications

Phenoxy-(Chloro)n-Boron Subnaphthalocyanines: Alloyed Mixture, Electron-Accepting Functionality, and Enhanced Solubility for Bulk Heterojunction Organic Photovoltaics

Phenoxy-(Chloro)n-Boron Subnaphthalocyanines: Alloyed Mixture, Electron-Accepting Functionality, and Enhanced Solubility for Bulk Heterojunction Organic Photovoltaics

Straightforward and Relatively Safe Process for the Fluoride Exchange of Trivalent and Tetravalent Group 13 and 14 Phthalocyanines

Highly Thermostable, Non‐oxidizable Indium, Gallium, and Aluminium Perfluorophthalocyanines with n‐Type Character

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Phenoxy-(Chloro)_n-Boron Subnaphthalocyanines: Alloyed Mixture, Electron-Accepting Functionality, and Enhanced Solubility for Bulk Heterojunction Organic Photovoltaics

Phenoxy-(Chloro)_n-Boron Subnaphthalocyanines: Alloyed Mixture, Electron-Accepting Functionality, and Enhanced Solubility for Bulk Heterojunction Organic Photovoltaics