The technology giant previewed the concept design at its annual developer conference, held in California.
Samsung released its first foldable smartphone, the Galaxy Fold, in the UK in September.
That device consists of a traditional screen on the front, which then opens out to reveal a larger, tablet-sized screen inside the phone.
However, Samsung’s new concept – which the company did not name – showed a smartphone screen folding in half horizontally to become more compact, much like so-called “clamshell” mobile phones, such as the Motorola Razr, which become popular in the late 1990s and early 2000s.
Those devices used a hinge between the screen and number keys to fold the device together.
The Korean firm’s Hyesoon Jeong said making mobile devices more compact was a key potential benefit of future foldable phones.
“This is just the beginning. With Galaxy Fold, we created a device that enhances the experience when it unfolds – it instantly gives you more space to work and play. But the amazing thing with the foldable technology is that it can also become more compact,” she said.
“This brand new form factor we’re now exploring will not only easily fit in your pocket, but it also changes the way you use your phone, even when you take photos and videos.”
Foldable smartphones are a growing trend in the tech industry – Chinese phone giant Huawei is due to launch its own foldable – the Mate X – in China next month.
Motorola is also widely expected to unveil a new, foldable screen version of the Razr clamshell mobile phone, first launched in 2004, in November.