Long lifetime emission from screen printing carbon nanotubes over 45,000 h at 1.27 mA/cm2 with 10% duty ratio

• A novel CNT paste, which contains agglomerated CNT bundles, was prepared.
• An emitter was fabricated by screen printing method using the CNT paste.
• A low number density of sparse bundles of agglomerated CNTs was formed as emission sites.
• The field emission measurement from the emitter was continued for more than 5 years.
• A long time operation of field electron emission over 45,000 h was achieved.

A long time operation of field electron emission over 45,000 h was achieved using the screen printing carbon nanotube (CNT) emitter fabricated on an ITO coated glass substrate. The measurement was carried out in an ultra-high vacuum chamber at around 3 × 10− 7 Pa in pressure with continuously applying voltage of rectangular pulses at 743 V or 730 V peak, 60 Hz frequency and 10% duty ratio. The emission current corresponding to the voltage pulse at 1.27 mA/cm2 density was repeatedly and reproducibly observed for more than 5 years. Because the operated condition was 10 times higher at the current density than that of the conventionally developed field emission lamps (FELs), the expected lifetime of the presented emitter will be 450,000 h though the vacuum level of the measurement was extremely higher than that of the actual operation of FELs. By investigating the morphology of the emitter after terminating the operation, it was found that sparse bundles of agglomerated CNTs were standing in the long lifetime CNT emitter.