Scaling theory for percolative charge transport in molecular semiconductors: Correlated versus uncorrelated energetic disorder

Ab initiocharge-carrier mobility model for amorphous molecular semiconductors

“…The c dependence is the same as for the EGDM, in accordance with the conclusion in Ref. [11] that the c dependence at not too high c only depends on the shape of the DOS.…”

“…Another important difference is that the ECDM predicts a much stronger F dependence than the EGDM. The c dependence of both models was shown to be essentially the same [11]. Good agreement between measured T -dependent current density-voltage (J -V ) characteristics of hole-only devices of α-NPD [N,N -Di(1-naphthyl)-N,N -diphenyl-(1, 1 -biphenyl)-4,4 -diamine] and those calculated with both the EGDM and ECDM could be obtained, but with different values of σ and N t : σ = 0.14 eV, N t = 0.20 × 10 27 m −3 for the EGDM and σ = 0.10 eV, N t = 3.7 × 10 27 m −3 for the ECDM [12].…”

“…It was suggested, however, that the presence of dipole moments in organic semiconductors can give rise to spatial correlation between the site energies [2,3], leading to the correlated disorder model (CDM). Later, it was realized that, apart from the dependence of μ on temperature T and electric field F , there is a strong dependence on the carrier concentration c [4][5][6][7][8][9][10][11], giving rise to extended versions of the GDM and CDM, the EGDM and ECDM, respectively. Percolation effects in the charge transport inherent to disordered systems, which become dominant at low T , are fully accounted for in the EGDM and ECDM.…”

Effects of Gaussian disorder on charge carrier transport and recombination in organic semiconductors

“…Recently, Cottaar et al showed that a 1/ T 2 dependence is also expected for transport in a Gaussian DOS when reorganization plays a role. The C coefficient is a function of the ratio between the reorganization energy and σ , and its measurement may thus be used to determine the relative role of reorganization 10, 11. Time‐of‐flight (TOF) mobility measurements 12 and analyses of the current–voltage ( J ( V )) characteristics of unipolar sandwich‐type single layer devices yield indeed often a 1/ T 2 temperature dependence 12, although also a 1/ T dependence has been obtained from such studies 13.…”

Полевая Диффузия В Неупорядоченных Органических Материалах В Условиях Заполнения Глубоких Состояний

“…Формаль-но, энергетическую зависимость r(E) нетрудно учесть (см. далее уравнение (10)), однако анализ возможного вида такой зависимости для других моделей темпов переходов (например, модели Маркуса [17,18]), а также анализ применимости концепции транспортного уровня в этом случае (фактически, эта концепция применена в работе [18]) выходят за рамки данной работы. Следующее приближение находим, учитывая произ-водную по времени в уравнении (2) в нулевом при-ближении.…”