Thermally stimulated photoluminescence in disordered organic materials

Kadashchuk, A.; Skryshevskiĭ, Yu. A.; Vakhnin, A.; Ostapenko, N. I.; Arkhipov, V. I.; Emelianova, E. V.; Bäßler, H.

doi:10.1103/physrevb.63.115205

Cited by 72 publications

(82 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Eq. ͑6͔͒ ͑this conclusion is also supported by previous studies [28][29][30] ͒ and it shifts toward deeper tail states of the DOS distribution with further lowering temperature, 21 so it eventually approaches the Fermi level F which features a much-flattened temperature dependence. This is depicted in the Fig.…”

Section: B Low-temperature Regionsupporting

confidence: 76%

“…II B. Interestingly, that the presented EMA theory predicts a transition to a Mott-type VRH regime at low enough temperatures and large carrier density. The principal reason for this effect is that the effective transport energy level t depends on temperature 21,[28][29][30] and shifts toward deeper tail states of the DOS with lowering temperature. A Mott-type VRH regime establishes when t becomes close to the Fermi level F .…”

Section: B Origin Of the Mnr-type Behavior In A Gaussian-type Hoppinmentioning

confidence: 99%

See 1 more Smart Citation

Temperature dependence of the charge carrier mobility in disordered organic semiconductors at large carrier concentrations

et al. 2010

Self Cite

View full text Add to dashboard Cite

Temperature-activated charge transport in disordered organic semiconductors at large carrier concentrations, especially relevant in organic field-effect transistors ͑OFETs͒, has been thoroughly considered using a recently developed analytical formalism assuming a Gaussian density-of-states ͑DOS͒ distribution and MillerAbrahams jump rates. We demonstrate that the apparent Meyer-Neldel compensation rule ͑MNR͒ is recovered regarding the temperature dependences of the charge carrier mobility upon varying the carrier concentration but not regarding varying the width of the DOS. We show that establishment of the MNR is a characteristic signature of hopping transport in a random system with variable carrier concentration. The polaron formation was not involved to rationalize this phenomenon. The MNR effect has been studied in a OFET based on C 60 films, a material with negligible electron-phonon coupling, and successfully described by the present model. We show that this phenomenon is entirely due to the evolution of the occupational DOS profile upon increasing carrier concentration and this mechanism is specific to materials with Gaussian-shaped DOS. The suggested model provides compact analytical relations which can be readily used for the evaluation of important material parameters from experimentally accessible data on temperature dependence of the mobility in organic electronic devices. Experimental results on temperature-dependent charge mobility reported before for organic semiconductors by other authors can be well interpreted by using the model presented in this paper. In addition, the presented analytical formalism predicts a transition to a Mott-type charge carrier hopping regime at very low temperatures, which also manifests a MNR effect.

show abstract

Section: B Low-temperature Regionsupporting

confidence: 76%

Section: B Origin Of the Mnr-type Behavior In A Gaussian-type Hoppinmentioning

confidence: 99%

Temperature dependence of the charge carrier mobility in disordered organic semiconductors at large carrier concentrations

et al. 2010

Self Cite

View full text Add to dashboard Cite

show abstract

“…It should be noted that a rather similar TSL peak was observed before in the methyl substituted ladder-type of poly(para-phenylene) (MeLPPP), [34] mer. The TSL curve of MeLPPP is given for comparison (Fig.…”

Section: Thermally Stimulated Luminescencementioning

confidence: 96%

Aggregate States and Energetic Disorder in Highly Ordered Nanostructures ofpara‐Sexiphenyl Grown by Hot Wall Epitaxy

Kadashchuk

Andreev

Sitter³

et al. 2004

Adv Funct Materials

Self Cite

View full text Add to dashboard Cite

We report on photoluminescence (PL) and thermally stimulated luminescence (TSL) in highly ordered nanostructures of para‐sexiphenyl (PSP) grown by hot wall epitaxy (HWE). A low‐energy broad band is observed in the PL spectra that can be attributed to the emission from molecular aggregates. While the intrinsic exciton emission in steady‐state PL dominates at low temperatures, the emission from aggregates increases with elevating temperature and its magnitude depends sensitively on film preparation conditions. Time‐resolved PL measurements showed that the aggregate emission decays with a life‐time of ≈ 4 ns, which is approximately an order of magnitude larger than the lifetime of singlet excitons. TSL data suggests the presence of an energetically disordered distribution of localized states for charge carriers in PSP films, which results from an intrinsic disorder in this material. A low‐temperature TSL peak with the maximum at around 30 K evidences for a weak energy disorder in PSP films, and has been interpreted in terms of a hopping model of TSL in disordered organic materials.

show abstract

“…In materials with significant disorder, charge transport is usually described in the framework of a hopping model in combination with, for instance, kinetic Monte Carlo (KMC) simulations, the concept of a transport level, effective-medium theory [6][7][8][9][10][11] , or percolation theory. [12][13][14][15][16][17][18] In the hopping regime, charge transport is governed by the thermally activated hopping of charge carriers within the manifold of localized states.…”

Section: Introductionmentioning

confidence: 99%

Role of band states and trap states in the electrical properties of organic semiconductors: Hopping versus mobility edge model

2013

View full text Add to dashboard Cite

We compare the merits of a hopping model and a mobility edge model in the description of the effect of charge-carrier concentration on the electrical conductivity, carrier mobility, and Fermi energy of organic semiconductors. We consider the case of a composite electronic density of states (DOS) that consists of a superposition of a Gaussian DOS and an exponential DOS. Using kinetic Monte Carlo simulations, we apply the two models in order to interpret the recent experimental data reported for n-doped C 60 films. While both models are capable of reproducing the experimental data very well and yield qualitatively similar characteristic parameters for the density of states, some discrepancies are found at the quantitative level.

show abstract

Thermally stimulated photoluminescence in disordered organic materials

Cited by 72 publications

References 37 publications

Temperature dependence of the charge carrier mobility in disordered organic semiconductors at large carrier concentrations

Temperature dependence of the charge carrier mobility in disordered organic semiconductors at large carrier concentrations

Aggregate States and Energetic Disorder in Highly Ordered Nanostructures ofpara‐Sexiphenyl Grown by Hot Wall Epitaxy

Role of band states and trap states in the electrical properties of organic semiconductors: Hopping versus mobility edge model

Contact Info

Product

Resources

About