Highly Deformable Transparent Au Film Electrodes and Their Uses in Deformable Displays

With emerging interest in foldable and stretchable displays, the need to develop transparent deformable electrode and interconnection is increasing. Even though metal films have been standard electrodes in conventional electronic devices due to their high conductivity and well-established process, they have never been used for transparent deformable electrodes. We present highly conductive transparent deformable Au film electrodes and use them to fabricate a foldable perovskite light-emitting diode (PeLED) and a biaxially stretchable alternating current electroluminescence (ACEL) display. We exhibit the formation of an ultrathin (6 nm) continuous Au film on an anisotropic conductive ultrathin film (ACUF) of amorphous carbon. The ultrathin Au film was first formed on an ACUF-coated Si wafer (4 in. scale) through metal evaporation and transferred to the polymer substrates by a simple and effective water-assisted delamination process. Then, a hybrid electrode (ACUF/ACUF/Au) was produced as the transparent deformable electrode. Complicated interconnections could be created by metal deposition through a mask. The electrical conductance of the hybrid electrode was not affected by the crack formation in the Au film during electrode folding, crumpling, and stretching. We reveal the reason why the hybrid electrode can maintain such excellent electrical stability under deformation.