Flexible, Wearable Organic Light‐Emitting Fibers Based on PEDOT:PSS/Ag‐Fiber Embedded Hybrid Electrodes for Large‐Area Textile Lighting

Abstract Organic light emitting diodes (OLEDs), which possess wonderful device performance and mechanical robustness have been extensively explored in textile lighting applications. In this work, an ITO‐free, PEDOT:PSS/Ag‐fiber hybrid transparent conducting electrode (TCE) embedded in polymeric substrate (denoted as hybrid‐fiber TCE henceforth) for the fabrication of large‐area OLEDs is designed. The optimum hybrid‐fiber TCE with a pitch of 150 µm shows extraordinarily low sheet resistance (R_sheet = 1.3 Ω ▫⁻¹) and exceptional mechanical flexibility, exhibiting ≈100% R_sheet retention at a bending radius of up to ≈0.5 mm. The device performance of the resulting OLEDs based on hybrid‐fiber TCEs (fiber‐OLEDs) is on‐par with that of ITO‐based OLED analogues. More fascinatingly, organic light emitting fibers (OLEFs), obtained via slitting the fiber‐OLEDs, display a maximum luminance efficiency of ≈38.2 cd A⁻¹ and a maximum external quantum efficiency of ≈10.9%, which surpasses all previously reported results. In addition, the OLEFs are mechanically robust and able to withstand a high degree of deformation, thus can be woven into fabric matrix for smart textile application. The vacuum‐free, scalable fabrication of the high performance OLEFs demonstrated herein is significant for the development of extremely large‐area smart textile applications.