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Intrinsic degradation in 100 nm AlQ3 OLED device with strong luminescence was observed while nearly no degradation in 50 nm AlQ3 device with weak luminescence was observed for the same operation time. Based on the EL and PL measurements, it was suggested that penetration of AlQ3 molecules into NPB layer resulted in the increase of electron leakage current, and thus significant loss of current efficiency. A plausible Coulomb effect induced intrinsic degradation mechanism was therefore proposed to explain the experimental results.

The forming/destruction mechanism of conducting filament is essential in understanding the behavior of resistance-memory device. On the basis of filamentary theory, we systematically studied the different electrical performances of both planar and vertical sandwich (metal/organic/metal) memory devices. Bias induced morphological change in gap devices are monitored using scanning electron microscopy system equipped with probes. The in situ images directly demonstrate that with bias increasing, metal clusters emerge inside the channel and further cause sudden switching of device resistance. After clarifying the roles of electrodes and sandwiched organic layer, we conclude a field-dependent filament formation and organics-assistant filament destruction mechanism for resistance memory phenomenon, which should generally exist in all organic electronic devices with metal electrodes.

Two peaks are observed in the capacitance–voltage (C–V) characteristics of electron-transport fullerene (C60 or C70)/Bphen based devices. The experimental results suggest that the mobile carriers generated from unintentional doping and trapped carriers are the origins of these two peaks, just the same as those of hole-transport devices. In addition, the polarity of one C–V peak voltage (the voltage corresponding to the peak capacitance) reverses as the Bphen layer thickness increases. The transient photo-voltage (TPV) signals show a polarity reversal of the internal electric field, confirming the related phenomenon.

Capacitance–voltage ( C – V ) characteristics of organic molecular semiconductors attracted much research interest recently, but no convincing physical mechanism has been established so far. In this work, the C – V characteristics of pentacene-based devices have been systematically investigated at various frequencies. Only one peak occurs when the measuring frequency is less than 3 kHz or greater than 8 kHz. While within the frequency range between the two, two C – V peaks are observed with quite different dependence on temperature, which suggests that the origins of these two C – V peaks are respectively mobile holes and trapped carriers. This conclusion is also experimentally validated with the C – V characteristics of intentionally doped devices.