A modulus-engineered multi-layer polymer film with mechanical robustness for the application to highly deformable substrate platform in stretchable electronics

Mechanical robustness and deformability of substrate platforms are essential for high-performance stretchable electronics. However, there are still challenges because of rigid island design for device protecting that induces large modulus mismatch and impedes the out-of-plane deformation. Herein, a substrate platform with superb mechanical durability and deformability is newly devised by introducing a multi-layer polymer film (MLPF), where the modulus of each layer was engineered precisely range from 10(5) to 10(9) Pa. The modulus-engineered MLPF was integrated monolithically onto various elastomer substrates via sequential film deposition using initiated chemical vapor deposition (iCVD). The developed substrate platform exhibited outstanding robustness against various modes of deformations. Especially the tensile deformation, MLPF structure enhanced mechanical durability by 10(2) times than a single-layer island structure while keeping the strain on the island below 1 % even with the 99 % of global strain. The developed substrate platform was applied for amorphous Indium-Gallium Zinc oxide TFT array. The TFT performances were maintained even under 30 % of tensile strain and they were fully retained after 10(5) times of repeated tensile deformation. The newly suggested substrate platform and design rule of MLPF structure will serve as a guideline for integration of future stretchable/wearable electronics achieving superb mechanical robustness and long-term operation.