Clean energy: An ink-jet printer for making prototype solar
cells at the National Renewable Energy Laboratory. The biggest
advantage, van Hest says, is that ink-jet printing, unlike
screen printing, does not involve applying pressure to the
silicon wafer. That makes it possible to use far thinner wafers,
he says. In conventional solar cells, the wafers are about 200
micrometers thick. “If you go any thinner than that, most of
them will break” during manufacturing, van Hest says. “If you go
to a noncontact method, you don’t have to worry about that. You
can use cells as thin as a hundred micrometers, or even thinner.
That means you can save 50 percent on the cost of silicon.” NREL
decided to use iTi Solar’s printers, as opposed to those from
other manufacturers, for two main reasons. The first is the
accuracy of the system: the printers can apply ink with an
accuracy of within 1 micrometer, as opposed to 10 to 15
micrometers with other systems, van Hest says. It’s also easy to
adapt to working with different i