Temperature dependence of cesium carbonate-doped electron transporting layers on organic light-emitting diodes

[Display omitted] •The current density (J) of Alq:Cs2CO3 OLED increased for ETLs from 100 to 300Å.•The J of TPBI:Cs2CO3 OLED increased for ETLs from 100 to 600Å.•The J increased with increasing temperatures from 10 to 300K.•The luminance (L) increased with increasing temperatures from 10 to 300K.•Th...

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Bibliographic Details
Published in:Synthetic metals 2015-11, Vol.209, p.128-134
Main Authors: Fu, Richard, Forsythe, Eric, Shi, Jianmin, Srour, Merric, Blomquist, Steven, Morton, David
Format: Article
Language:English
Subjects:
Carbonates
Cesium
Cesium carbonate doping
Contact
Current density
Devices
Electroluminescence
Electron injection
Electron transport
OLED devices
Organic materials
Phenyls
Temperature dependence
Transporting
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Summary:[Display omitted] •The current density (J) of Alq:Cs2CO3 OLED increased for ETLs from 100 to 300Å.•The J of TPBI:Cs2CO3 OLED increased for ETLs from 100 to 600Å.•The J increased with increasing temperatures from 10 to 300K.•The luminance (L) increased with increasing temperatures from 10 to 300K.•The difference between Alq and TPBI ETLs may be due to the nitrogen electron pairs. The 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 (Cs2CO3) doping for organic light emitting devices. The current-voltage and light emission characteristics were measured as a function of the Cs2CO3 doped ETL thickness at both room temperature and cryogenic (10–300K). The current density (J) for the Alq:Cs2CO3 ETL device increased for an ETL thickness between 100 and 300 Å, with no further increase in the ETL beyond 300Å, indicating an electron injection limited contact. Conversely, the J for the TPBI:Cs2CO3 ETL device did not saturate for increasing ETL thicknesses confirming the TPBI:Cs2CO3 devices have a near-ohmic cathode contact. The correlation of current density–voltage (J–V) and luminance-voltage (L–V) for both Alq:Cs2CO3 and TPBI:Cs2CO3 devices were studied over temperatures from 10 to 300K. Both increased with increasing temperature; however, Cs2CO3-doped TPBI devices were more effective than Cs2CO3-doped Alq devices. The observed differences between Alq and TPBI may be attributed to the exposed nitrogen electron pair in the electronic structure.
ISSN:0379-6779
1879-3290
DOI:10.1016/j.synthmet.2015.07.025