Volatile copper(I) benzoates with variable degrees of fluorination are used for p-doping of organic hole-transport layers in single-carrier devices, charge-generation layers, and in organic light-emitting diodes. The charge-transport abilities of the doped materials correlate with the degree and position of the fluorination on the aromatic ring of the carboxylate groups.

We demonstrate the usage of caesium phosphate (Cs3PO4) as a low-cost n-dopant for conductivity enhancements of the electron transport layer in organic light-emitting diodes (OLEDs). Up to 9 orders of magnitude, reaching 2.3 × 10−5 S/cm with only 10% dopant concentration in 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline single-carrier devices, were achieved. Luminance current voltage and impedance spectroscopy measurements confirmed the increased conductivities of the single carrier devices in green light-emitting diodes. Constant operation voltages of below 4 V were realized independently of the electron transport layer (ETL) thickness, which was varied from 50–150 nm. Dielectric constants were modeled by usage of the least squares method. Measured and calculated capacitances based on the geometric properties and modeled dielectric constants varied by less than 1.3% for doped OLEDs, confirming the highly conductive nature of Cs3PO4-doped ETLs and demonstrating that a highly conductive electron transport layer can be understood as an extended cathode.

Electrically doped, organic transport layers are important for today's high efficiency organic (opto-)electronic devices. Doped organic layers have a strongly increased free charge carrier density compared to their undoped counterparts and also improve the charge carrier injection from adjacent electrodes into the organics. For practical applications, especially in optoelectronics, these layers have to have low absorption in the wavelength range of interest. The two nearly colorless p-and n-doping materials, rhenium heptoxide and cesium carbonate, are investigated focusing on their conductivity enhancement, injection improvement, and voltage drop over doped transport layers in organic light emitting diodes. They show very good doping properties already at moderate doping concentrations and prove that they can be used in variable thicknesses without a significant voltage increase. This makes them cheap, low absorbing alternatives to today's, well-established doping systems. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).