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A B S T R A C TThe temperature dependence and electronic transport properties of 1, 3, 5-tri(1-phenyl-1H-benzo [d] imidazol-2-yl) phenyl (TPBI) and 8-hydroxyquinoline aluminum (Alq) electron transporting layers (ETL) have been investigated as a function of cesium carbonate (Cs 2 CO 3 ) doping for organic light emitting devices. The current-voltage and light emission characteristics were measured as a function of the Cs 2 CO 3 doped ETL thickness at both room temperature and cryogenic (10-300 K). The current density (J) for the Alq:Cs 2 CO 3 ETL device increased for an ETL thickness between 100 and 300 Å, with no further increase in the ETL beyond 300 Å, indicating an electron injection limited contact. Conversely, the J for the TPBI: Cs 2 CO 3 ETL device did not saturate for increasing ETL thicknesses confirming the TPBI:Cs 2 CO 3 devices have a near-ohmic cathode contact. The correlation of current density-voltage (J-V) and luminancevoltage (L-V) for both Alq:Cs 2 CO 3 and TPBI:Cs 2 CO 3 devices were studied over temperatures from 10 to 300 K. Both increased with increasing temperature; however, Cs 2 CO 3 -doped TPBI devices were more effective than Cs 2 CO 3 -doped Alq devices. The observed differences between Alq and TPBI may be attributed to the exposed nitrogen electron pair in the electronic structure.Published by Elsevier B.V.

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