Large work function difference driven electron transfer from electrides to single-walled carbon nanotubes

A difference in work function plays a key role in charge transfer between two materials. Inorganic electrides provide a unique opportunity for electron transfer since interstitial anionic electrons result in a very low work function of 2.4-2.6 eV. Here we investigated charge transfer between two different types of electrides, (Ca2N](+)center dot e(-) and [Ca24Al28O64](4+)center dot 4e(-), and single-walled carbon nanotubes (SWNTs) with a work function of 4.73-5.05 eV. [Ca2N](+)center dot e(-) with open 2-dimensional electron layers was more effective in donating electrons to SWNTs than closed cage structured [Ca24Al28O64](4+)center dot 4e(-) due to the higher electron concentration (1.3 x 10(22) cm(-3)) and mobility (similar to 200 cm(2) V-1 s(-1) at RT). A non-covalent conjugation enhanced near-infrared fluorescence of SWNTs as high as 52%. The field emission current density of electride-SWNT-silver paste dramatically increased by a factor of 46 000 (14.8 mA cm(-2)) at 2 V mu m(-1) (3.5 wt% (Ca2N](+)center dot e(-)) with a turn-on voltage of 0.85 V mu m(-1).