Imprint lithography of Ag NCs: In one embodiment, a plasmonic nanostructure with Ag NCs was fabricated according to the following steps: First, commercial glass (Delta-technology) was purchased, and cleaned with acetone, IPA, DI water solution for 10 min, in order, respectively. Then, thermal imprint resist (NXR-1000) was spin-coated at 3000 rpm for 1 min on the glass substrate, and pre-baked at 150° C. for 5 min. It was covered by a master template which has nano-pillar array nanostructures. Then, the stack of master template and substrate was heated up to 130° C. and subsequently pressed into the substrate at 300 psi for 5 min, finally cooled to room temperature and de-molded in a Nanonex NX-2600 nanoimprint tool. Oxygen descum process was performed to the substrate for removing any residual layer. Ag nanocrystal dispersion was spincoated on the imprinted pattern on the glass substrate, for fabricating silver plasmonic nanostructure. The substrate was dipped to the 1% ammonium thiocyanate in methanol, and cleaned with IPA solvent for ligand exchange. Finally, the imprinted resist was removed by lift-off in acetone sonication for 1 min leaving nanopatterned Ag nanocrystal array on the glass substrate. Alternatively, the imprinting procedure in the previous embodiment may be used to imprint Ag NCs electrodes on a thermally oxidized Si substrate. In a particular embodiment, PbSe NCs may be deposited on a substrate with imprinted electrodes and then undergo ligand exchange according to the solid ligand exchange method of flowchart 10.