Intense Pulsed Light Sintering of Cu@Ag Core-Shell Nanoparticles: Durable Flexible Electrodes and Electroluminescent Visual Feedback

Abstract Oxidation susceptibility and insufficient service reliability remain major limitations for Cu-based conductive inks in flexible electronics. Here, size-tunable Cu@Ag core–shell nanoparticles were processed by millisecond intense pulsed light (IPL) sintering to establish a rapid route toward conductive and durable flexible electrodes. Comparative finite-element thermal analysis and electrical measurements establish a practical IPL processing window, while electron microscopy and complementary diffraction analysis support energy-dependent interparticle connection and localized Cu–Ag interfacial reconstruction without assuming homogeneous alloying throughout the film. The sheet resistance reaches a minimum of 0.06 Ω/sq at 5.0 J/cm2, whereas 4.5 J/cm2 is selected as the practical baseline because it provides a more favorable balance among conductivity, film integrity, environmental stability, flexibility, adhesion, and limited cumulative substrate heating. Films processed within this window maintain low resistance during damp-heat and cryogenic exposure and exhibit stable electrical behavior during repeated bending. At the device level, the 4.5 J/cm2 electrode enables a contact-separation triboelectric nanogenerators (TENG) with an open-circuit voltage of 275.45 V and a peak power density of 0.71 W/m2. In otherwise identical alternating-current electroluminescent (ACEL) devices, increasing the electrode-processing energy from 1.5 to 4.5 J/cm2 markedly increases luminance, directly linking the IPL-defined electrode state to device performance. The integrated patterned platform further enables tactile-position visual feedback. These results establish an evidence-based processing-thermal response-structure-reliability-device relationship for IPL-sintered Cu@Ag NPs flexible electrodes.