drift-diffusion current in organic diodes有机二极管中漂移扩散电流.pdfVIP

Drift-diffusioncurrentinorganicdiodes

GillesHorowitz

CNRS--LPICM,EcolePolytechnique,91128Palaiseau,France

Becausetheconductivityoforganicsemiconductorsisverylow,ausefulmodelfortheorganic

diodeconsistsoftreatingtheorganiclayerasaninsulator,anapproximationoftenreferredtoas

themetal-insulator-metal(MIM)model.Moreover,thedominantchargecarrierinjectionprocessis

diffusion,sothatamodifiedSchottky’stheorycanbeusedtoderiveasimpleanalyticalequation

forthecurrentvoltagecurveofthediode.Here,wecarriedoutafullanalysisoftheMIMmodel

fortheorganicdiode.WeshowthatSchottky’stheoryisonlyvalidwhenchargeinjectionispoor,

7thatis,forhighinjectionbarriers.Whentheinjectionbarrierislowered,thecurrentgivenby

1Schottky’stheoryisstillvalidintheweakinjectionregime,whentheappliedpotentialislowerthan

0thediffusionpotential.However,itbecomeslargelyoverestimatedinthestronginjectionregime.

2Wealsoshowthatinthestronginjectionregime,thecurrentgivenbytheMIMmodelmergeswith

Mott-Gurnery’sspace-charge-limitedregime.

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gilles.horowitz@polytechnique.edu

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I.INTRODUCTION

Threemechanismsareusuallyinv