NOVELTY - A cathode comprising an electrically conductive nonmetallic layer in low-resistance electrical contact with a semiconductive organic layer.    USE - The cathode is useful in optoelectronic devices for converting electrical energy into optical energy or optical energy into electrical energy, preferably an organic light emitting device (OLED) containing a heterostructure for producing electroluminescence, especially an organic laser or photodetectors, phototransistors, solar cells and light emitting diodes. The low-reflectivity OLEDs may be particularly useful in high contrast displays and for eliminating microcavity effects in stacked organic light emitting devices (SOLEDs); particularly for reliable high-resolution full color flat panel displays (e.g. passive matrix or active matrix displays) and heads-up displays. The optoelectronic devices can also be used in a vehicle, a computer, a television, a printer, a large area wall, theater or stadium screen, a billboard or a sign. OLEDs containing a phosphorescent dopant compound produce a highly saturated red emission that peaks at 640 nm (claimed). The azlactone-related dopant compounds produce electroluminescence in bands centered in the wavelength region of one of the primary colors and the phosphorescent decay rate is rapid enough to meet the requirements of a display device.    ADVANTAGE - The nonmetallic cathodes are highly transparent (e.g. optical transmission at least 85%) and have electron-injection properties comparable to prior art semitransparent metallic cathodes (e.g. optical transmission = 60-70%). The emission of the dopant may be varied by selectively varying the substituents or by modifying the structure of the base compound that produces the emission. The compounds can be readily deposited as a thin layer by vacuum deposition techniques to form an OLED that is prepared entirely from vacuum-deposited organic materials. The nonmetallic cathode may be in contact with an organic protection layer that is capable of assisting in the injection and transport of electrons from the cathode to the luminescent zone of the OLED and can also protect the underlying organic layers from damage during deposition of the cathode layer. The organic protection layer may be in direct contact with the electron transporting layer in the luminescent zone of the device or there may be an additional electron transporting layer between these two layers which further assists in transporting electrons to the luminescent zone of the OLED. The phosphorescent decay process utilizes exciton triplet state energy that is typically wasted in a conventional OLED via a radiationless energy transfer and relaxation process. The new OLEDs have a stability under ambient environmental conditions for a few days that is comparable to prior art devices and a much decidedly greater shelf life stability, compared with TPP-doped devices. TOLEDs according to the present invention show only a 2-fold drop in light output at 180 hours, whereas prior art TOLEDs have a 4-fold drop in light output over the same time interval. Additionally, the photoluminescent quantum yields are greater than prior art compounds (e.g. up to 90% versus 10%).    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for    (1) An optoelectronic device for converting electrical energy into optical energy or vice versa comprising the above cathode;    (2) An organic light emitting device containing a heterostructure for producing electroluminescence and comprising the above cathode;    (3) A method of fabricating an optoelectronic device including the step of depositing an electrically conductive nonmetallic layer on an organic layer, to form an interface region at the surface of the organic layer that lowers the voltage drop across the two layers when the two layers are used as a cathode in an optoelectronic device;    (4) A method for fabricating a cathode having an electrically conductive nonmetallic layer, including the step of forming an interface region which provides a low-resistance electrical contact between the electrically conductive nonmetallic layer and the semiconductive organic layer.    (5) A method of forming an organic light emitting device comprising preparing a heterostructure for producing electroluminescence and where the preparation process includes the step of forming the above cathode.