Intrinsically Stretchable Polymer Semiconductor Doping System Enabled by Ambient Oxygen Molecules for Skin Electronics

Despite significant development of intrinsically stretchable polymer semiconductors, their doping systems are still in its infancy. Herein, we introduce a spontaneous doping by oxygen molecules in the intrinsically stretchable nanofibrous polymer semiconductors. Oxygen molecules in the air are chemically adsorbed on the semiconductor nanofibers to act as an acceptor, which is a diffusion-controlled process dependent on oxygen partial pressure and humidity. The doping significantly elevates the hole concentration of the nanofiber, surpassing the initial value by two orders of magnitude and reaching a level of 3.37 × 10¹⁷ cm^-2. The stretchable field-effect transistors with doped semiconductors show significantly enhanced transconductance, field-effect mobility, and on/off ratio with a high air stability compared to the transistors with undoped semiconductors. To verify the feasibility of the enhanced performance of the doped stretchable semiconductor, we fabricate active-matrix arrays, inverters, and logic gates (NOR and NAND) that are fundamental elements of electronic circuits and exhibits excellent operational reliability under 30% bi-axial strain.