YUAN Jian-ting, PENG Ying-quan, YANG Qing-sen, XING Hong-wei, LI Xun-shuan. Effect of Mobility on the Distribution of Electric Field and Carrier Density in Single Layer Organic Light Emitting Devices[J]. Chinese Journal of Luminescence, 2008,29(6): 962-966
YUAN Jian-ting, PENG Ying-quan, YANG Qing-sen, XING Hong-wei, LI Xun-shuan. Effect of Mobility on the Distribution of Electric Field and Carrier Density in Single Layer Organic Light Emitting Devices[J]. Chinese Journal of Luminescence, 2008,29(6): 962-966DOI:
The performance of organic light emitting devices (OLEDs) is closely related to the electric field intensity and carrierdensity distribution in the organic layer.Based on the drift-diffusion theory for themotion of charge carriers
we considered the OLED structure consists of a single layerof luminescentor ganicmaterial sandwiched between twometallic electrodes
the contacts between themetallic electrodes and organicmaterial are ohmic.We adopted themethod of numerical calculation to study the potential
electric field intensity
carrier density and recombination rate in the organicmaterial.The results shown these:(1) when holes and electrons have the same mobility
the distribution of the potential
electric field
carrierdensity and recombination rate is symmetrical.This is because the in fluence of two differentcarriers injection is the same.Mostcarriers distribute near the electrodes and decrease very fast
the interface of metal/semiconductor contact is just like a carrier packet and the carrierdensity is very low in the middle of the device
so the electric fieldsnear the two contacts aremuch stronger than that in themiddle.(2)When themobility of holes and electronsdiffersgreatly
the highermobility carriers can notonly distribute near the injecting electrode butalso transmit to another electrode.However
the lowermobility carriers distri-butemainly near the injecting electrode.When themobility difference of electron and hole is small
the distri-bution of the carriers isbetween the above two cases.When the ratio of holemobility to electronmobility changes
the position of themaximum of the electric fieldmoves to the electrode from which the lowmobility carriers are in jected.