Amorphous diamond can emit electrons in vacuum when applied with an electrical field of only a few volts per micron. It is also extremely thermionic so the emitted current can increase millions times when heated to only a few hundreds degrees centigrade. As a result, amorphous diamond can be a thermal generator or a solar cell. The energy conversion efficiency can have much higher (e.g. 50%) than that (e.g. 15%) of silicon based solar cells that can absorb only a narrow spectrum of sun light. As a solar cell, amorphous diamond has another advantage that its radiation hardness is the highest of all materials, hence, its thermal electricity efficiency will not attenuate as does the solar cell based on photo electric semiconductorls. An immediate application of amorphous diamond is to coat it on electron emitting electrodes, such as that used as cold cathode fluorescence lamps (CCFL) that illuminate liquid crystal displays (LCD) for fornote books and television sets. Amorphous diamond can dramatically reduce the turn-on voltage to lit CCFL so the lamp life can be greatly extended. Moreover, the electrical current can be increased to enhance the brightness of the light.