New polymer light-emitting devices can be stretched like rubber

Stretchable electronics is a new emerging class of modern electronics as it can be potentially useful for a wide range of applications including wearable electronics, “smart skins,” and minimally invasive biomedical devices. Today’s conventional inorganic electronic devices are brittle and certain flexibility may only be obtained by using ultrathin layers of inorganic materials. Furthermore, these various devices are either flexible (can be bent) or stretchable (i.e., discrete LED chip interconnected with stretchable electrodes) but they lack intrinsic stretchabilty (every part of the device is stretchable).

 

Now, researchers at the UCLA Henry Samueli School of Engineering and Applied Science have demonstrated, for the first time, an intrinsically stretchable polymer light-emitting device. UCLA postdoctoral fellow Zhibin Yu and the team led by Qibing Pei, UCLA professor of materials science and engineering, developed a simple process to fabricate transparent polymer light-emitting devices using single-walled carbon nanotube (SWNT)-polymer composite electrodes. The interpenetrating networks of SWNT and the polymer matrix in the surface layer of the composites lead to low sheet resistance, high transparency, high compliance and low surface roughness.

 

The metal-free devices can be linearly stretched up to 45 % and the composite electrodes can be reversibly stretched by up to 50 % with little change in sheet resistance. The devices are fabricated by roll lamination of two composite electrodes that sandwich an emissive polymer layer.

 

Additionally, the devices uniquely combine mechanical robustness and the ability for large-strain deformation because of the shape memory property of the composite electrodes. This development will provide a new direction for the field of stretchable electronics.