The authors investigated a full sealed flat-panel light source, which is based on a triode structure with a metal mesh gate electrode and uses a carbon nanotube cold cathode. It has a flat surface luminance distribution with good uniformity, a stable luminance of 12 000 cd/m(2), and a luminous efficiency that was measured to be 14.5 lm/W. It also shows a high color rendering index of 88 and a wide optical emission spectrum. Further, its application as thin film transistor-liquid-crystal display (TFT-LCD) backlight was demonstrated and the resulted performance of the TFT-LCD display was studied and compared to the commercial TFT-LCD products, which use the cold-cathode fluorescent lamp backlight and light emitting diode backlight. It is shown that the light transmission ratio in the TFT-LCD module using our light source is similar to 8%, as compared to similar to 4% of the commercial products. With this and the very high luminance, our light source is very useful to the situation, in which the TFT-LCD screen is employed to work under outdoor sunshine conditions. (C) 2008 American Vacuum Society.