Oxidation-resistant and Ultrastable AZO-encapsulated AgNWs/CA-SWCNTs films enabling sustained EMI shielding and joule heating

Flexible and transparent conductive films are extensively employed in window defogging, wearable physiotherapy devices, transparent electrodes, electromagnetic interference shielding, flexible displays, etc. Though silver nanowires (AgNWs) and low-dimensional carbons (e.g., CNTs) and Ti₃C₂Tₓ MXene accelerate field development, persistent challenges such as CNTs dispersion instability and AgNWs oxidation susceptibility limit practical implementation. This study designed a multilayer composite film on PET: a cross-network conductive layer of AgNWs and citric acid-modified single-walled carbon nanotubes (CA-SWCNTs), encapsulated by an aluminum-doped zinc oxide (AZO) protective layer via sol-gel method. AgNWs with high aspect ratio (average diameter 74 nm, length 53 μm) were synthesized by polyol method as the conductive backbone. CA-SWCNTs enhanced hydrophilicity and interfacial bonding, forming a stable conductive/thermal network. By suppressing oxidation and reflection, the AZO encapsulation layer increased the transmittance at 550 nm from 81.3 % to 82.1 % while maintaining a low sheet resistance of 5.4 Ω/sq. The composite films delivered an EMI shielding efficiency of 28.9 dB (8.2 GHz), achieved rapid Joule heating to 120 °C within 90 s at 7 V, demonstrated robust stability over 5500 s of cyclic operation, and exhibited environmental endurance with merely 19.9 % sheet resistance increase after 480 h air exposure as well as a 22.1 % increase after 100 cycles of tape peeling tests. This work provides an innovative strategy for multifunctional flexible transparent devices.