CALCIUM ELECTRODES IN POLYMER LEDS

The qualitative results of a study of the fabrication of Ca/CN-PPV/ITO polymer light-emitting diodes (LEDs) in ultrahigh vacuum (UHV) are re ported, where CN-PPV is a cyano-substituted poly(p-phenylenevinylene). If the calcium electrode is deposited on a clean polymer surface unde r UHV conditions, the device yield is very low, and, for the devices t hat do function, the electroluminescence lifetimes are extremely short . If the calcium electrode is deposited in the presence of a high part ial pressure of oxygen, the diodes are much better in terms of yield, lifetime and luminescence.