A prototypical organic light-emitting diode (OLED), anode/organic layers/cathode, is investigated via bias-dependent capacitance measurement of two-layer (HTL/ETL) and four-layer (HIL/HTL/EML/ETL) structure at low frequency. As applied voltage was larger than the built-in voltage, the capacitance is augmented by diffusion capacitance with increasing the forward bias voltage. In contrast, the capacitance dropped quickly. It is possibly due to the voltage drop in the bulk and conductivity modulation occurred by high carrier concentration for much higher forward biases, eventually showing negative for two-layer OLEDs. We infer that the phenomena were resulted from the extremely thin OLED structure, just like short p-n semiconductor diodes. This diffusion capacitance exhibiting like short-diode behavior also can be measured in C-V curves of single-layer structure OLED.
|Number of pages||5|
|Journal||Thin Solid Films|
|State||Published - 1 Mar 2006|
|Event||Proceedings of the Third Asian Conference on Chemical Vapor Deposition (Third Asian-CVD), Third Asian CVD - |
Duration: 12 Nov 2004 → 14 Nov 2004
- Diffusion capacitance
- Non-combination carriers