Performance improvement of macroscopical film of gold nanoparticles as temperature sensor derived from its mono-crystallinity

Macroscopically monocrystalline, self-assembled monolayers (M2-SAM) of gold nanoparticles coated with oleylamine (Au@OLA NPs) are achieved by optimizing their surface charges, which can create proper long-rang order electrostatic repulsive interactions to help balance the strong van der Waals attractive force and the hy-drophobic repulsion force between neighboring Au NPs. The mono-crystallinity of the resulting M2-SAM of Au@OLA NPs is embodied in unconventional Moire ' patterns beyond the low magnification imaging limit of scanning electron microscopy. The mono-crystallinity not only makes the M2-SAM of Au@OLA NPs be SERS substrates for quantitative analysis, but also enables them to fabricate temperature sensors with high precision and broad measurement span. Both the electrical resistivity-based temperature sensor with a precision of 0.001 degrees C in the range of-243 to 77 degrees C and the SERS-based temperature sensor with a precision of 0.5 degrees C in a range of 33 to 130 degrees C are implemented.