Thermoplasmonic dissipation in gold nanoparticle–polyvinylpyrrolidone thin films†
Thermal dissipation of plasmon energy from gold nanoparticles (AuNPs) dispersed in transparent polymers is important to biotherapeutics, optoelectronics, sensing, and chemical separations. This work assessed heat dissipated from power extinguished by 16 nm AuNPs with negligible Rayleigh scattering cross-sections dispersed into subwavelength, 70 nm polyvinylpyrrolidone (PVP) films at interparticle separations much less than the resonant wavelength. In contrast to super-wavelength films with particles at separations near the resonant wavelength, measured optical extinction and temperature increase per NP (°C per NP) decreased as AuNP concentration increased: °C per NP decreased 22% and optical extinction per NP decreased 35% as AuNP concentration increased from 1.01 to 5.06 × 1015 NP per cm3. The trend and magnitude of measured values were consistent with those from a priori description of optical extinction per NP from Maxwell Garnett effective medium theory (EMT) and from coupled dipole approximation (CDA). Optical power extinguished by the films exhibited a trend and magnitude consistent with finite element analysis (FEA) of thermal dissipation from subwavelength films at particle separations of 130 to 76 nm. Comparing measured values with results from EMT, CDA, and FEA distinguished contributions to plasmon-resonant optical extinction and heat dissipation. These results support design and adaptive control of thermal dissipation from plasmonic films.