Twenty-three percent of teens mainly go online using their phones and not a desktop or laptop computer, versus 15 percent of adults, the poll by the Pew Research Center's Internet and American Life Project showed.

Seventy-eight percent of teens have a cell phone, and 47 percent of those have smartphones. That means that 37 percent of all teens have smartphones, up from 23 percent in 2011, Pew said.

Mary Madden, a Pew researcher, said the smartphone figure was significant since teenagers typically set trends for Internet use, as they did with social media and texting.