Different agglomeration properties of PC<sub>61</sub>BM and PC<sub>71</sub>BM in photovoltaic inks – a spin-echo SANS study

Bernardo, Gabriel; Melle‐Franco, Manuel; Washington, A. L.; Dalgliesh, Robert M.; Li, Fankang; Mendes, Adélio; Parnell, Steven R.

doi:10.1039/c9ra08019h

Cited by 14 publications

(12 citation statements)

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“…This became particularly evident when preparing concentrated fullerene solutions (~20 mg•mL −1 ) for 13 C NMR analysis-while all the C 70 derivatives were soluble or partially soluble in deuterated chloroform CDCl 3 (C 70 bearing the carbazole unit showed to be a little less soluble), the C 60 derivatives were not soluble in CDCl 3 , and could be completely solubilized only in CS 2 (the most powerful solvent for fullerenes). This higher solubility of C 70 derivatives in organic solvents, compared to the corresponding C 60 derivatives, has been previously reported [54,55]. The 1 H NMR spectra of the C 60 derivatives are quite simple and shows the characteristic features of a N-methyl-(60)fulleropyrrolidine mono-adducts.…”

Section: Resultssupporting

confidence: 77%

Thiophene- and Carbazole-Substituted N-Methyl-Fulleropyrrolidine Acceptors in PffBT4T-2OD Based Solar Cells

et al. 2020

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The impact of fullerene side chain functionalization with thiophene and carbazole groups on the device properties of bulk-heterojunction polymer:fullerene solar cells is discussed through a systematic investigation of material blends consisting of the conjugated polymer poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3‴-di(2-octyldodecyl)-2,2′;5′,2″;5″,2‴-quaterthiophen-5,5‴-diyl)] (PffBT4T-2OD) as donor and C60 or C70 fulleropyrrolidines as acceptors. The photovoltaic performance clearly depended on the molecular structure of the fulleropyrrolidine substituents although no direct correlation with the surface morphology of the photoactive layer, as determined by atomic force microscopy, could be established. Although some fulleropyrrolidines possess favorable lowest unoccupied molecular orbital levels, when compared to the standard PC71BM, they originated OPV cells with inferior efficiencies than PC71BM-based reference cells. Fulleropyrrolidines based on C60 produced, in general, better devices than those based on C70, and we attribute this observation to the detrimental effect of the structural and energetic disorder that is present in the regioisomer mixtures of C70-based fullerenes, but absent in the C60-based fullerenes. These results provide new additional knowledge on the effect of the fullerene functionalization on the efficiency of organic solar cells.

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Section: Resultssupporting

confidence: 77%

Thiophene- and Carbazole-Substituted N-Methyl-Fulleropyrrolidine Acceptors in PffBT4T-2OD Based Solar Cells

et al. 2020

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“…These measurements should be sensitive to a concentration above 0.005 vol % for particles of radius 500 nm and 0.001 vol % for particles of radius 1 μm. 33 The SESANS measurements unequivocally support the volume-weighted DLS results in that they both show a very low or effectively zero volume fraction of dispersed lead-based colloids present at larger particle sizes. To validate our approach and to illustrate what would be seen if such dispersed particles were present in solution, we have included SESANS data for a 3 μm diameter silica particle dispersion in D 2 O, this was at 0.1% by volume.…”

Section: Resultssupporting

confidence: 56%

“… 30 , 32 More recently Bernardo et al used the technique to study the degree of dissolution of a range of organic photovoltaic relevant fullerenes (PC 61 BM and PC 71 BM) to ascertain the maximum solubility in these highly opaque solutions. 33 They were able to observe the presence of colloidal aggregates in solution arising from incomplete dissolution of the fullerene species as they went beyond the solubility limit.…”

Section: Introductionmentioning

confidence: 99%

Exploring Nanoscale Structure in Perovskite Precursor Solutions Using Neutron and Light Scattering

et al. 2022

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Tailoring the solution chemistry of metal halide perovskites requires a detailed understanding of precursor aggregation and coordination. In this work, we use various scattering techniques, including dynamic light scattering (DLS), small angle neutron scattering (SANS), and spin–echo SANS (SESANS) to probe the nanostructures from 1 nm to 10 μm within two different lead-halide perovskite solution inks (MAPbI 3 and a triple-cation mixed-halide perovskite). We find that DLS can misrepresent the size distribution of the colloidal dispersion and use SANS/SESANS to confirm that these perovskite solutions are mostly comprised of 1–2 nm-sized particles. We further conclude that if there are larger colloids present, their concentration must be <0.005% of the total dispersion volume. With SANS, we apply a simple fitting model for two component microemulsions (Teubner–Strey), demonstrating this as a potential method to investigate the structure, chemical composition, and colloidal stability of perovskite solutions, and we here show that MAPbI 3 solutions age more drastically than triple cation solutions.

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“…Solutions of fullerenes and their derivatives remain the focus of attention for researchers in various fields, , including photovoltaics, , electrochemistry, and biomedicine. , Therefore, new publications continue to report on the properties of fullerenes in non-aqueous ,− and aqueous ,,,, solutions. In polar solutions, fullerenes readily form colloids.…”

Section: Introductionmentioning

confidence: 99%

Unexpected Colloidal Stability of Fullerenes in Dimethyl Sulfoxide and Related Systems

et al. 2022

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It is known that fullerenes are poorly soluble in polar solvents, but readily form colloidal solutions in such media. These solutions are typically solvophobic (hydrophobic when prepared in water), that is, thermodynamically unstable colloidal systems with negatively charged particles. To understand the stability factors of a colloidal system, the thresholds for coagulation of a sol or suspension by electrolytes are of key importance. While hydrosols and aqueous suspensions coagulate at concentrations of 1:1 inorganic electrolytes about 0.1− 0.2 M, in acetonitrile and methanol, the corresponding critical concentrations of coagulation are ca. 3 orders of magnitude lower. Given the wide variety of properties of organic solvents, it seemed important to complete the picture to study solvents with more basic properties. This is all the more reasonable since electrophilic fullerenes are in fact Lewis acids. Our choice was dimethyl sulfoxide, DMSO, and related solvent systems. The colloidal solutions of fullerenes C 60 and C 70 in DMSO and N,N-dimethyl formamide, DMF, are unexpectedly easy to prepare by mechanical methods, and addition of water leads to formation of relatively stable organo-hydrosols. UV−visible spectra and dynamic light scattering were used to characterize the solutions of C 60 and C 70 in DMSO, benzene−DMSO, acetonitrile−DMSO, and benzene−acetonitrile−DMSO systems, as well as in DMF. Our present study demonstrated that, in contrast to organosols in methanol and acetonitrile, colloids of C 70 and C 60 fullerenes in DMSO and DMF are surprisingly as stable with respect to electrolytes as the corresponding hydrosols are. Such high stability is caused by the non-DLVO interactions, or, in terms proposed by Churaev and Derjaguin, by the so-called structural effect. These results shed light on the nature of the solvation of colloidal fullerene particles in solvents of various chemical natures.

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Different agglomeration properties of PC₆₁BM and PC₇₁BM in photovoltaic inks – a spin-echo SANS study

Abstract: Fullerene derivatives are used in a wide range of applications including as electron acceptors in solution-processable organic photovoltaics.

Cited by 14 publications

References 73 publications

Thiophene- and Carbazole-Substituted N-Methyl-Fulleropyrrolidine Acceptors in PffBT4T-2OD Based Solar Cells

Thiophene- and Carbazole-Substituted N-Methyl-Fulleropyrrolidine Acceptors in PffBT4T-2OD Based Solar Cells

Exploring Nanoscale Structure in Perovskite Precursor Solutions Using Neutron and Light Scattering

Unexpected Colloidal Stability of Fullerenes in Dimethyl Sulfoxide and Related Systems

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Different agglomeration properties of PC61BM and PC71BM in photovoltaic inks – a spin-echo SANS study

Abstract: Fullerene derivatives are used in a wide range of applications including as electron acceptors in solution-processable organic photovoltaics.

Cited by 14 publications

References 73 publications

Thiophene- and Carbazole-Substituted N-Methyl-Fulleropyrrolidine Acceptors in PffBT4T-2OD Based Solar Cells

Thiophene- and Carbazole-Substituted N-Methyl-Fulleropyrrolidine Acceptors in PffBT4T-2OD Based Solar Cells

Exploring Nanoscale Structure in Perovskite Precursor Solutions Using Neutron and Light Scattering

Unexpected Colloidal Stability of Fullerenes in Dimethyl Sulfoxide and Related Systems

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Different agglomeration properties of PC₆₁BM and PC₇₁BM in photovoltaic inks – a spin-echo SANS study