Dielectric studies of Alq3 and transport mechanisms

Jeong, Yong Seok; Tománek, David; Moliton, André; Ratier, Bernard; Antony, Rémi; Veriot, G.

doi:10.1016/s0379-6779(01)00622-1

Cited by 8 publications

(5 citation statements)

References 7 publications

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“…However, for ac conductivity, the charge carrier will hop from a site i to another site j (during τ H ) where it will relax during τ 0 (related to ac electrical parameters of the previous section). Consequently, a hopping transport mechanism can be postulated, as reported earlier for several organic semiconductors [59,64,65]. In general, the trend of the conductivity with frequency, in such disordered materials, obeys the following relation and can be consequently analysed by Jonscher's power law [41,66]:…”

Section: Equivalent Electrical Circuit and Trap Distributionmentioning

confidence: 74%

“…Impedance spectroscopy has been shown to be a useful tool to understand the transport mechanisms and interface processes in different organic electronic devices either for chemical sensors [58] or optoelectronic components (OLEDs [59] and organic BHJ solar cells [60]).…”

Section: Ac Study: Impedance Spectroscopymentioning

confidence: 99%

“…The unique properties of these materials make them promising for organic electronic and optoelectronic applications, such as chemical sensors [1][2][3], light-emitting diodes [4][5][6], thin film transistors [7][8][9] and solar cells [10][11][12]. Three important families of organic materials have been investigated for these purposes: small molecules (Alq 3 , phthalocyanines) [8,13], conjugated polymers [4,6,14] and macrocycles like ionophores, such as cyclodextrin [3,[15][16][17] and calix [n]arene derivatives [2,[18][19][20]. The last one has attracted increased attention in recent years due to their better preparation and purification as well as their possible deposition as thin films by thermal evaporation [19,21] or spin coating [20,22].…”

Section: Introductionmentioning

confidence: 99%

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Optical and electrical properties of semi-conducting calix[5,9]arene thin films with potential applications in organic electronics

Dridi

Benzarti-Ghédira

Vocanson

et al. 2009

Semicond. Sci. Technol.

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Indium tin oxide (ITO) substrates have been functionalized by several substituted calix [n]arene (n = 5 or 9) derivatives using spin coating to fabricate organic diode devices. The effect of rim size and side substituents has been investigated by UV-visible absorption spectrophotometry. The energy band gaps of these calixarene derivative thin films have been found in the 1.166-1.450 eV range. The electrical properties of ITO/calix[n]arene/Al diodes have been studied by current-voltage measurement showing an ohmic behaviour at low voltage. The I(V) characteristics could be modelled by a space-charge-limited current (SCLC) mechanism at high applied bias voltage. The ac electrical transport of calix[5,9]arene derivatives has been studied over a wide range of bias voltage and frequency by impedance spectroscopy. The device had been accurately modelled, for a frequency between 100 Hz and 10 MHz, by a single parallel resistor and capacitor network in series with a resistance. A dielectric relaxation time in the ms range and a transport mechanism controlled by an exponential trap distribution were deduced from the fit of the experimental data. The evolution of electrical parameters with chemical structure (rim size and substituent) has been discussed. The conductivity σ (ω) evolution with frequency and bias voltage was studied for ITO/calix[n]arene/Al devices. The dc conductivity σ dc for these devices has been determined. The ac conductivity σ ac showed a variation in angular frequency as A.ω s with a critical exponent s < 1 suggesting a hopping conduction mechanism at high frequency and a microscopic picture of the relaxation and hopping processes has been proposed.

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Section: Equivalent Electrical Circuit and Trap Distributionmentioning

confidence: 74%

Section: Ac Study: Impedance Spectroscopymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Optical and electrical properties of semi-conducting calix[5,9]arene thin films with potential applications in organic electronics

Dridi

Benzarti-Ghédira

Vocanson

et al. 2009

Semicond. Sci. Technol.

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“…Since its discovery, tris(8-hydroxyquinoline) aluminum (III) (Alq 3 ) has been a prominent molecule in modern organic light-emitting diodes (OLEDs) because of its electroluminescent properties and excellent stability. − Most studies to date have focused on understanding the mechanism of charge transport and the characteristics of electroluminescence of Alq 3 -based OLEDs. − However, studies taking advantage of temperature-programmed desorption (TPD), to our knowledge, are not available. Thermal annealing of the polymer-based OLEDs has been a subject of recent attention. − It was found that thermal treatment results in a remarkable improvement in the long-term stability of the device.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3] Most studies to date have focused on understanding the mechanism of charge transport and the characteristics of electroluminescence of Alq 3 -based OLEDs. [1][2][3][4][5][6][7][8][9] However, studies taking advantage of temperature-programmed desorption (TPD), to our knowledge, are not available. Thermal annealing of the polymer-based OLEDs has been a subject of recent attention.…”

Section: Introductionmentioning

confidence: 99%

Thermal Desorption of Tris(8-hydroxyquinoline)aluminum (III) (Alq₃) on Cu(111)

2003

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The thermal properties of tris(8-hydroxyquinoline)aluminum (III) (Alq 3 ), widely used in organic light-emitting diodes, have been examined on Cu(111) using temperatureprogrammed desorption (TPD). Two molecular desorption peaks are evident in TPD. Strikingly, the lower temperature (R) peak at ∼450 K develops first, but is not saturating, whereas the higher temperature (β) peak at ∼500 K appears later and grows more rapidly than the (R) peak. For the model proposed, as-deposited Alq 3 forms an amorphous phase that converts to a crystalline phase in competition with desorption during TPD and a possible crystalline formation from the deposition. Consistent with this model, annealing at 400 K slowly shifts the subsequent TPD intensity from the (R) to the (β) peak. TPD after heating to 470 K and rapidly cooling to <350 K exhibits a strong (β), but no (R), peak.

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2023

Defects in Organic Semiconductors and Devices

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Dielectric studies of Alq3 and transport mechanisms

Cited by 8 publications

References 7 publications

Optical and electrical properties of semi-conducting calix[5,9]arene thin films with potential applications in organic electronics

Optical and electrical properties of semi-conducting calix[5,9]arene thin films with potential applications in organic electronics

Thermal Desorption of Tris(8-hydroxyquinoline)aluminum (III) (Alq₃) on Cu(111)

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Dielectric studies of Alq3 and transport mechanisms

Cited by 8 publications

References 7 publications

Optical and electrical properties of semi-conducting calix[5,9]arene thin films with potential applications in organic electronics

Optical and electrical properties of semi-conducting calix[5,9]arene thin films with potential applications in organic electronics

Thermal Desorption of Tris(8-hydroxyquinoline)aluminum (III) (Alq3) on Cu(111)

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Thermal Desorption of Tris(8-hydroxyquinoline)aluminum (III) (Alq₃) on Cu(111)