Samsung researchers in South Korea have designed and built a prototype of a seamless foldable Active-matrix organic light-emitting diode (AMOLED) display. The display's mechanical and optical robustness were tested by performing 100,000 folding-unfolding cycles. The relative brightness at the junction decreased by just 6 percent, which is hardly recognizable by the human eye and so the deterioration can be considered negligible. The findings have been published in a recent issue of Applied Physics Letters.

The display consists of two AMOLED panels, silicone rubber (a hyperelastic material), a module case, and a protective glass cover (which not only prevents scratches but can also serve as a touch screen). The display has a very small folding radius of just 1 mm, so that one panel lies almost completely on top of the other when the display is folded at a 180° angle. "All the materials in a foldable window unit (glasses and silicone rubber) must have almost the same optical properties and attach to each other strongly without any optical property change," coauthor HongShik Shim of the Samsung Advanced Institute of Technology told PhysOrg.

In their study, the researchers explain that most flexible displays, which are becoming increasingly more viable and interesting to mobile companies, are bendable or rollable to avoid the creases that occur from folding a material completely in half. The researchers have overcome this problem by creating an AMOLED display with no visible crease: the key to pulling this off is to control the optical properties of the materials.

Some believe that foldable displays could be the future of mobile devices as they solve the problem of minimizing the size of the device while simultaneously maximizing the size of the display. A display that can fold completely in half is the best way to achieve this goal, but so far it has been a challenge to eliminate the visible crease between panels. Now that obstacle has been surmounted, at least in the prototype phase.