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The fabrication of the transparent conducting electrode (TCE) by incorporation of carbon nanotubes (CNTs) into indium tin oxide and polythiophene by mixing and then spin coating is demonstrated. The electrical measurements on the CNT-enhanced organic light-emitting devices (OLEDs) showed that increasing the CNT concentrations in the TCE films would increase the current density of the films at a fixed operating voltage.

Sapphire substrates coated with a gold (Au) layer in place of indium-tin-oxide (ITO) on glass substrates are used as hole-injecting anodes in organic light-emitting devices (OLEDs). Due to the unique quality of the sapphire/Au interface and match of Au work function with the highest occupied molecular orbital level of the adjacent hole transport layer (HTL), and the smoothness of the interface, he ITO-free OLED, achieved an increase in current efficiency by more than a factor of three.

A correlation between current 1/f noise and dark spot formation is reported. Our results show that the dark spot is primarily correlated to current 1/f noise slope; the higher the slope, the poorer the interface, and the more abnormal dark spot growth rate and the shorter lifetime. Besides, there is a correlation between current 1/f noise magnitude and the dark spot initial size. A higher 1/f noise magnitude generally indicates a larger dark spot initial size. A seemingly identical current-voltage curve does not render the same characteristics of dark spot formation, which can be clearly distinguished from the subtle difference in 1/f noise behavior. The noise measurement can be used to predicate device lifetime and degradation behavior. [ABSTRACT FROM AUTHOR]

Low-frequency noise characteristics of organic light-emitting diodes are investigated. Two noise components were found in experimental low-frequency noise records, namely: 1) 1/f Gaussian noise from device bulk materials and 2) an excessive frequency-related part of noise related to device interfaces or defects and traps. 1/f noise is said to be related to carrier mobility. Degradation, especially photo-oxidation of the electroluminescence polymer, is a possible reason that affects carrier mobility. The excessive part of noise is believed to be related to the carrier numbers and could come from the interface deterioration, defects and traps generation and furnish. The excessive part of noise increases much faster during device stress. This shows that the degradation related interface defects and traps is much faster. [ABSTRACT FROM AUTHOR]