Emission FTIR study of C60 thermal stability and oxidation

Vassallo, Anthony M.; Pang, Louis S. K.; Cole-Clarke, Peter; Wilson, Margaret

doi:10.1021/ja00020a086

Cited by 120 publications

(31 citation statements)

References 2 publications

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“…Molecular organic semiconductors have attracted great attention in order to meet the requirement of n-type organic TE materials. Fullerenes are one of the best n-type semiconductors with high electron mobility, low thermal conductivity (∼ 0.4 W/mK), 68 and excellent thermal stability 69 and it is ideal for many organic electronic Figure 8. Molecular structures of n-type semiconducting polymer P(NDI2OD-T2), the molecular dopant DMBI and the self-dopable PDI derivative, PDI-OH.…”

Section: N-type Organic Thermoelectric Materialsmentioning

confidence: 99%

Review—Organic Materials for Thermoelectric Energy Generation

Cowen

Atoyo

Carnie

et al. 2017

ECS J. Solid State Sci. Technol.

129

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Organic semiconductor materials have been promising alternatives to their inorganic counterparts in several electronic applications such as solar cells, light emitting diodes, field effect transistors as well as thermoelectric generators. Their low cost, light weight and flexibility make them appealing in future applications such as foldable electronics and wearable circuits using printing techniques. In this report, we present a mini-review on the organic materials that have been used for thermoelectric energy generation. The reduction in the effects of climate change, caused by the burning of fossil fuels, has recently been given increased emphasis by major world governments and it is therefore necessary to consider the efficiency of the methods we currently use to generate energy. It has previously been estimated that 63% of global energy consumption is wasted with the major form of this waste being heat.1,2 It is therefore important to develop methods of reconverting this wasted heat back in to useful forms of energy, such as electricity.Thermoelectric generators (TEG) are a promising technology which make use of a process known as the Seebeck effect for heat recovery. The Seebeck effect can be described as two dissimilar conductors or semiconductors connected thermally in parallel and electrically in series and exposed to a temperature gradient causing a difference in voltage between the two materials.3,4 In a TEG one p-type and one ntype semiconductor make use of the Seebeck effect by connecting one to the other electrically in series and thermally in parallel; a general device setup is shown in Figure 1. By connecting the two components, by a junction which is heated, the n-type component of the device transports electrons from the hot junction to a heat sink while the p-type material transports positively charged holes along the same direction of the temperature gradient. The reverse is also possible if the holes and electrons flow away from a cold connecting junction to a heated point at the end of each semiconductor, this induces a constant cooling at the junction through the Peltier effect. 4,5The quantification of the Seebeck effect, in a specific material, is given by the Seebeck coefficient, α, and is the open circuit voltage of a material subjected to a temperature gradient, commonly with units on the scale of μVK −1 to mVK −1 . 6 A materials overall efficiency in the conversion of heat to electricity is given by the dimensionless figure of merit, ZT, defined as,where σ is the electrical conductivity and κ is the thermal conductivity. [6][7][8] It is therefore necessary for thermoelectric materials to have a high electrical conductivity and a low thermal conductivity making electrically conducting metals inappropriate for thermoelectric applications due to their high thermal conductivities and low z E-mail: m.j.carnie@swansea.ac.uk; derya.baran@kaust.edu.sa; b.c.schroeder@qmul .ac.uk Seebeck coefficients. The ideal thermoelectric materials should be an electrical crystal to maximize σ and at the s...

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Section: N-type Organic Thermoelectric Materialsmentioning

confidence: 99%

Review—Organic Materials for Thermoelectric Energy Generation

Cowen

Atoyo

Carnie

et al. 2017

ECS J. Solid State Sci. Technol.

129

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“…This effect is reversible (subsequent exposure of the sample to air causes an increase in resistance). Above 470 K, the onset of a chemical reaction of oxygen with C60-molecules was reported [8]. This irreversible reaction is accompanied by an increase in the resistance.…”

Section: Methodsmentioning

confidence: 94%

“…Much research has been devoted to the studies of the interaction of oxygen with C60 fullerene [1][2][3][4][5][6][7][8][9][10][11]. Molecular oxygen is reported to be absorbed but not to react with the C60-molecules at room temperature (e.g.…”

Section: Introductionmentioning

confidence: 99%

Influence of Oxygen Impurities on Electrical Properties of Fullerene C₆₀

1995

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We present high temperature dc, ac and contactless microwave conductivity results on solid-state C60 (films and crystals) from room temperature up to 850 K. Heating pristine samples, which were exposed to the ambient atmosphere, under dynamic vacuum at first leads to a reduction of the electrical resistance and finally, above 700 K, to an increase in the resistance. The decrease is ascribed to oxygen desorption and the increase to the chemical reactivity of residual chemisorbed oxygen with the C60 host molecules, respectively. Samples, annealed above 800 K, display a reversible temperature dependence of the resistance. The high temperature regime of their resistance exhibits an activated behaviour with an universal activation energy of 2Ea = 1.85 ± 0.04 eV for crystals and films, which is identical to the HOMO-LUMO splitting of the C 60 -molecules.

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“…In principle, qualitative analysis of crystallized substituted oxides can also be performed through X-ray diffraction (XRD) studies, although this is a laborious approach [62][63][64][65][66][67][68]. Infrared spectra have been reported for several oxides [2,12,17,19,20,41,58,85,[89][90][91], but such spectra have seldom been used for identification.…”

Section: Qualitative and Quantitative Analysesmentioning

confidence: 99%