Charge transport mechanisms

Charge transport mechanisms
– Crystalline solids and molecular solids exhibit different transport mechanisms.
– Atomic solids have intra-molecular transport (band transport).
– Molecular solids have inter-molecular transport (hopping transport).
– Different mechanisms result in different charge mobilities.
– Disordered solids have weak localization effects and reduced mobility.
– Determination of charge transport mechanisms in ultrathin copper phthalocyanine vertical heterojunctions
– Drift mobilities in amorphous charge-transfer complexes of trinitrofluorenone and poly-n-vinylcarbazole
– Description of charge transport in disordered organic materials
– Description of charge transport in amorphous semiconductors
– Disorder in charge transport in doped polymers

Concentration of localized states
– Carrier mobility depends on the concentration of localized states.
– Nearest-neighbour hopping describes low concentrations.
– Incoherent hopping transport occurs at low concentrations.
– Variable range hopping describes high concentrations.
– Nearest-neighbour dependence is valid for very dilute systems.

Temperature dependence
– Mott formula describes temperature-dependent conductivity.
– Relationship holds for a large range of field strengths.
– Increased temperature may increase or decrease carrier mobility.
– Applied electric field can increase mobility through thermal ionization.
– Increased concentration of localized states increases mobility.

AC conductivity
– AC conductivity in disordered semiconductors follows a specific form.
– Real and imaginary parts of AC conductivity have specific expressions.
– Random barrier model predicts AC conductivity in disordered solids.
– RBM AC conductivity representation was improved in 2008.
– Scaled frequency and DC conductivity are involved in the improved representation.
– The universal dielectric response
– AC hopping transport in disordered materials
– The random free-energy barrier model for AC conduction in disordered solids
– Universality of AC conduction in disordered solids
– Density of states on fractals: fractons

Ionic conduction
– Electrical resistance of thin-film electrolytes depends on applied electric field.
– Thickness reduction and field-induced conductivity enhancement improve conductivity.
– Field dependence of current density through an ionic conductor can be described.
– Random walk model with independent ions under a periodic potential is assumed.
– Inter-site separation affects the field dependence of current density. Source:  https://en.wikipedia.org/wiki/Charge_transport_mechanisms