Broadband absorption in Au nanoparticle-decorated chlorophyll b for biophotonic applications

This paper reports a broadband absorption of gold nanoparticle-decorated chlorophyll b. Chlorophyll b was extracted from spinach. Au nanoparticles were synthesized by chemical method. Structural and optical characterization of chlorophyll-b and Au nano-particles were also studied. Current-voltage characteristics of chlorophyll-b and Au nanoparticle-decorated chlorophyll b were also studied by fabricating devices using etched ITO glass. Chlorophyll-b has a strong absorption in the blue region at 435 nm and in the red region at 665 nm, whereas Au nanoparticle has its plasmonic peak at 535 nm. Au nanoparticle-decorated chlorophyll b gives a broad absorption spectrum ranging from 315 nm to 1025 nm due to the interaction between chlorophyll b molecules with Au nano-particles.