Electrically Stable Organic Permeable Base Transistors for Display Applications

Vertical organic permeable base transistors (OPBT) can drive large current densities of kA cm(-2) and achieve record-high transition frequencies of up to 40 MHz. They are therefore an interesting candidate for numerous applications, including the use in active-matrix organic light emitting display (AMOLED) backplanes. However, the transistor characteristics are required to be stable against electrical stress. Here, the threshold voltage shifts under current- and voltage-stress conditions over various temperatures and illumination conditions are investigated. OPBTs show excellent stability under the probed conditions, even at extended exposure to large on-state currents of 3 A cm(-2). The strongest shifts are observed at elevated temperatures, suggesting a temperature activation of the stress effect. On-state current stress scales linearly with the current density, while off-state stress is induced by the applied voltage. The effects of both kinds of stress are complementary and can compensate each other. It is found that the OPBT is perfectly suitable as a switching transistor in AMOLED displays.