Effect of positively charged particles on sputtering damage of organic electro-luminescent diodes with Mg:Ag alloy electrodes fabricated by facing target sputtering

We investigated the influence of the positively charged particles generated during sputtering on the performances of organic light-emitting diodes (OLEDs) with Mg:Ag alloy electrodes fabricated by sputtering. The number of positively charged particles increased by several orders of magnitude when the target current was increased from 0.1 A to 2.5 A. When a high target current was used, many positively charged particles with energies higher than the bond energy of single C–C bonds, which are typically found in organic molecules, were generated. In this situation, we observed serious OLED performance degradation. On the other hand, when a low target current was used, OLED performance degradation was not observed when the number of positively charged particles colliding with the organic underlayer increased. We concluded that sputtering damage caused by positively charged particles can be avoided by using a low target current

Short-time-scale threshold voltage shifts in organic field-effect transistors caused by dipoles on insulator surface

AbstractWe previously reported that dipoles on the surface of the gate insulator layer in organic transistors cause time decay of the drain current on time scales of less than 0.1s from the application of the gate voltage. In this study, we investigated the relationship between the time decay and magnitude of the gate voltage. We found that this time decay can be attributed to threshold voltage shifts unaccompanied by mobility changes. When the insulator surface has dipoles that can move somewhat, the threshold voltage shift has two components: one with a time scale of approximately 0.1s and the other with a time scale of tens of minutes