Highly Flexible and Mechanically Robust Ultrathin Au Grid as Electrodes for Flexible Organic Light-Emitting Devices

We report a highly flexible ultrathin Au grid with high mechanical robustness as transparent electrode for flexible organic light-emitting devices (OLEDs). The grids are introduced to an ultrathin Au film to improve its optical transmittance and mechanical performance. With the line width of 15 μm and the gap width of 30 μm, the optimal ultrathin Au grid presents a desirable transmittance of 88.7% at 550 nm and a sheet resistance of 36 Ω/sq. Owing to the reduced tensile stress by the ultrathin grid patterns, the flexible ultrathin Au grid exhibits extraordinary mechanical stability with maintained conductivity after 48 000 bending cycles under a bending radius of 1 mm. Flexible OLEDs with high flexibility and mechanical robustness have been obtained using the ultrathin Au grid as the transparent anode by maintaining 92% initial efficiency after 4200 bending cycles. Moreover, flexible OLEDs exhibit a significantly improved current efficiency in comparison to the devices based on the continuous Au or traditional ITO anode.