Specificity of<sup>13</sup>C NMR Shielding Calculations in Thiocarbonyl Compounds

Rozhenko, Alexander; Trachevsky, V.V.

doi:10.1080/10426500902947492

Cited by 8 publications

(14 citation statements)

References 52 publications

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“…46 Such rich chemistry of thiourea transformation leads to the hypothesis that some of the aforementioned non-volatile species may actually form during our sol-gel process and serve as surface ligands for CZTS NPs formed in-situ. 44,47 Previous study has revealed that the peak at 164 ppm indicates the presence of a triazine ring in which the carbon bonds with a -NH2 group, while the peak at 156 ppm indicates that the carbon bonds with a -NHgroup. Two reasons determine the choice of 13 C-SSNMR over routine liquid-phase 1 H-NMR.…”

Section: Resultsmentioning

confidence: 99%

Controlling Solid–Gas Reactions at Nanoscale for Enhanced Thin Film Morphologies and Device Performances in Solution-Processed Cu₂ZnSn(S,Se)₄ Solar Cells

et al. 2015

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Using Cu2ZnSn(S,Se)4 (CZTSSe) as a model system, we demonstrate the kinetic control of solid-gas reactions at nanoscale by manipulating the surface chemistry of both sol-gel nanoparticles (NPs) and colloidal nanocrystals (NCs). Specifically, we first identify that thiourea (commonly used as sulfur source in sol-gel processes for metal sulfides) can transform into melamine upon film formation, which serves as surface ligands for as-formed Cu2ZnSnS4 (CZTS) NPs. We further reveal that the presence of these surface ligands can significantly affect the outcome of the solid-gas reactions, which enables us to effectively control the selenization process during the fabrication of CZTSSe solar cells and achieve optimal film morphologies (continuous large grains) by fine-tuning the amount of surface ligands used. Such enhancement leads to better light absorption and allows us to achieve 6.5% efficiency from CZTSSe solar cells processed via a sol-gel process using nontoxic, low boiling point mixed solvents. We believe our discovery that the ligand of particulate precursors can significantly affect solid-gas reactions is universal to solid-state chemistry and will boost further research in both understanding the fundamentals of solid-state reactions at nanoscale and taking advantage of these reactions to fabricate crystalline thin film semiconductors with better morphologies and performances.

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Section: Resultsmentioning

confidence: 99%

Controlling Solid–Gas Reactions at Nanoscale for Enhanced Thin Film Morphologies and Device Performances in Solution-Processed Cu₂ZnSn(S,Se)₄ Solar Cells

et al. 2015

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“…However, this computationally demanding approach is not suitable even for medium-sized structures and hence the less superior approaches should be used instead. The BP86 level of theory was also shown to be useful for the 13 C nuclear shielding calculations of thiocarbonyl compounds, due to the cancellation of errors of a different nature …”

Section: Resultsmentioning

confidence: 99%

“…The BP86 level of theory was also shown to be useful for the 13 C nuclear shielding calculations of thiocarbonyl compounds, due to the cancellation of errors of a different nature. 57 We report here the first systematic computational study aimed at deriving 13 C NMR chemical shift values for carbenes at the DFT and MP2 levels of theory. The calculations were carried out both for the stable carbenes with the known experimental carbon NMR chemical shift values 59 and for the short-lived species (Table 4).…”

Section: ■ Methodological Details In Calculationsmentioning

confidence: 99%

On the Stability of Perfluoroalkyl-Substituted Singlet Carbenes: A Coupled-Cluster Quantum Chemical Study

2014

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A series of trifluoromethyl-substituted carbenes R-C(:)-CF3 (R = NMe2, OMe, F, PMe2, P(NMe2)2, P(N(Pr-i)2)2, SMe, Cl); (dimethylamino)(perfluoroalkyl)carbenes Me2N-C(:)-R (R = CF3, C2F5, n-C3F7, i-C3F7, and t-C4F9) and symmetrically substituted carbenes R-C(:)-R (R = NMe2, OMe, F, PMe2, SMe, Cl) have been investigated by means of quantum chemistry methods. Different levels of approximation were used, including the CCSD(T) approach also known in quantum chemistry as the "golden standard", in combination with three different basis sets (TZVP, cc-pVDZ, cc-pVTZ). Relative stabilities of carbenes have been estimated using the differences between the singlet and triplet ground state energies (ΔEST) and energies of the hydrogenation reaction for the singlet and triplet ground states of the carbenes. The latter seem to correlate better with stability of carbenes than the ΔEST values. The (13)C NMR chemical shifts of the methylidene carbon indicate the more high-field chemical shift values in the known, isolable carbenes compared to the unstable ones. This is the first report on the expected chemical shifts in the highly unstable singlet carbenes. Using these criteria, some carbene structures from the studied series (as, for instance, Me2N-C(:)-CF3, Me2N-C(:)-C3F7-i) are proposed as good candidates for the experimental preparation.

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“…Three experimental absolute shieldings of CH 3 X compounds were summarized previously [31]. CH 4 195.1 ppm [58,63] (this value has been often used as reference in theoretical papers [64][65][66][67]), CH 3 NO 2 126.9 ppm [59] (see also [68]), and TMS 188.1 ppm [58] (see also [64,[69][70][71][72][73][74][75][76]), the method that best reproduce these three values is MPW1PW91/6-311? ?G(d,p): 193.64, 123.68, and 188.33 ppm, respectively (see Table 1).…”

Section: Resultsmentioning

confidence: 99%

Influence of the basis set on the calculation of the absolute 13C shieldings of methyl derivatives (CH3X with X = CH3, CN, NH2, NO2, OH, F) with special emphasis in the cases of X = Cl, Br, SH, SeH, and PH2

Alkorta

Elguero

2010

Struct Chem

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Specificity of¹³C NMR Shielding Calculations in Thiocarbonyl Compounds

Cited by 8 publications

References 52 publications

Controlling Solid–Gas Reactions at Nanoscale for Enhanced Thin Film Morphologies and Device Performances in Solution-Processed Cu₂ZnSn(S,Se)₄ Solar Cells

Controlling Solid–Gas Reactions at Nanoscale for Enhanced Thin Film Morphologies and Device Performances in Solution-Processed Cu₂ZnSn(S,Se)₄ Solar Cells

On the Stability of Perfluoroalkyl-Substituted Singlet Carbenes: A Coupled-Cluster Quantum Chemical Study

Influence of the basis set on the calculation of the absolute 13C shieldings of methyl derivatives (CH3X with X = CH3, CN, NH2, NO2, OH, F) with special emphasis in the cases of X = Cl, Br, SH, SeH, and PH2

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Specificity of13C NMR Shielding Calculations in Thiocarbonyl Compounds

Cited by 8 publications

References 52 publications

Controlling Solid–Gas Reactions at Nanoscale for Enhanced Thin Film Morphologies and Device Performances in Solution-Processed Cu2ZnSn(S,Se)4 Solar Cells

Controlling Solid–Gas Reactions at Nanoscale for Enhanced Thin Film Morphologies and Device Performances in Solution-Processed Cu2ZnSn(S,Se)4 Solar Cells

On the Stability of Perfluoroalkyl-Substituted Singlet Carbenes: A Coupled-Cluster Quantum Chemical Study

Influence of the basis set on the calculation of the absolute 13C shieldings of methyl derivatives (CH3X with X = CH3, CN, NH2, NO2, OH, F) with special emphasis in the cases of X = Cl, Br, SH, SeH, and PH2

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Specificity of¹³C NMR Shielding Calculations in Thiocarbonyl Compounds

Controlling Solid–Gas Reactions at Nanoscale for Enhanced Thin Film Morphologies and Device Performances in Solution-Processed Cu₂ZnSn(S,Se)₄ Solar Cells

Controlling Solid–Gas Reactions at Nanoscale for Enhanced Thin Film Morphologies and Device Performances in Solution-Processed Cu₂ZnSn(S,Se)₄ Solar Cells