Embodiments include a package substrate, a method of forming the package substrate, and a self-assembled monolayers (SAM) layer. The package substrate includes a SAM layer on portions of a conductive pad, where the SAM layer includes light-reflective moieties. The package substrate also includes a via on a surface portion of the conductive pad, and a dielectric on and around the via, the SAM layer, and the conductive pad, where the SAM layer surrounds and contacts a surface of the via. The SAM layer may be an interfacial organic layer. The light-reflective moieties may include a hemicyanine, a cyclic-hemicyanine, an oligothiophene, and/or a conjugated aromatic compound. The SAM layer may include a molecular structure having a first end group of a first monolayer, an intermediate group, a fifth end group of a second monolayer, and one or more of a first and second light-reflective moieties.