Physical Review Letters · 2002 · 109 citations · 38 references
Natural SciencesChemistryPhysicsCondensed Matter PhysicsOptical MaterialsSpectroscopyOptical Properties Of SolidsOptical SpectroscopyOrganic SemiconductorsTerahertz PhotonicsTerahertz SpectroscopyUltrafast OpticsDispersive TransportPhotocarrier DynamicsPhotoconductivityPhotoexcitation MechanismsPicosecond SpectroscopyTerahertz Pump-probe SpectroscopyTransient Transmission SpectroscopyUltrafast Carrier Dynamics
We have measured transient photoconductivity in functionalized pentacene molecular crystals using ultrafast optical pump-terahertz probe techniques. The single crystal samples were excited using 800 nm, 100 fs pulses, and the change in transmission of time-delayed, subpicosecond terahertz pulses was used to probe the photoconducting state over a temperature range from 10 to 300 K. A subpicosecond rise in photoconductivity is observed, suggesting that mobile carriers are a primary photoexcitation. At times longer than 4 ps, a power-law decay is observed consistent with dispersive transport.
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