Achieving Low-Voltage Operation of Intrinsically-Stretchable Organic Light-Emitting Diodes

Abstract

A minimum operating voltage of intrinsically-stretchable organic light-emitting diodes (ISOLEDs) is always required for practical applications. However, the lack of protocols for the lamination complicates the task of attaining a reliable ISOLED without inducing degradation. Here, a solvent-vapor-assisted lamination (SVAL) method to reinforce the cathode interface is presented; this process lowers the operation voltage and increases the stretchability of ISOLEDs. Achieving a uniform contact and strong adhesion at the interface is the key to attaining reliable lamination. A cold-pressing (CP) treatment is applied first to reduce the surface roughness of silver nanowires before the surface embedding process. A subsequent solvent vapor treatment before the lamination partially solvated the surface of the active layer with an increase in the segmental motion of polymer chains, which substantially increases the interfacial adhesion after lamination. The combination of CP and SVAL treatments considerably reduces threshold voltage V-th (i.e., voltage at which current shows an abrupt increase for light-emission) from 6.7 to 2.7 V. The ISOLED also exhibts excellent mechanical stretchability, with no significant change in luminance under 30% strain. This study can assist in the development of practical applications of intrinsically-stretchable optoelectronic devices.