The optical response of materials is predicated on light-matter interactions in free space, subject to the laws of conservation of energy and momentum. Since the momentum of free space photons is negligible in comparison to that of electrons, optical transitions are only allowed among states that are vertically aligned in momentum space. This is the reason for the poor absorption of so called indirect semi- conductors, where the valence and conduction bands are misaligned. Silicon, which is the material of choice for photovoltaic solar cells, is a prime example. 

In a recent article, arXiv:2304.14521, it was demonstrated that light-matter interactions can be fundamentally changed using nanometrically confined photons. The momentum of the photon can be increased by 2-3 orders of magnitude by confining it on plasmonic nanoparticles, whereby the absorption of solar radiation in silicon can be enhanced by 2-3 orders of magnitude. This paves the way for thin-film Si-solar cells at a significant reduction in cost and materials consumption. 

To explore the concept and its implementation, a theoretical effort was launched at YSU, led by Drs. Vram Mughnetsyan and Aram Manaselyan, and supported by Hovhannes Haroyan, Armen Harutyunyan, and Professor Khachig Nerkararyan; and an experimental effort was launched at the Alikhanyan National Laboratory, led by Drs. Narek Margaryan and Eduard Aleksanyan. Prof. V. Ara Apkarian of UC Irvine, who is a coauthor of the original work, is advising the two groups, and the effort is being facilitated by the ARPA Institute.