We developed an ultrafast process for synthesizing a carbon-nanotube film using an atmospheric pressure plasma jet. The processing time is only 5 s. The synthesized material is then used as a counter electrode (CE) in a dye-sensitized solar cell (DSSC). With these Pt-free CEs, the assembled DSSCs show efficiency comparable to those of cells with CEs made by a conventional furnace calcination process. The energy consumption is estimated to be 500 J/cm2, which is about one-fifth that of the CE by conventional furnace process. It is therefore an ecofriendly, cost- and time-saving process for fabricating energy devices.