Development of a new ray model for understanding the coupling between dielectric spheres for photovoltaics with higher efficiency

Innenfor dette prosjektet etablerte vi et teoretisk rammeverk for en stråle-bølgekorrespondanse teori i en og to dimensjoner. Ved å bruke denne teorien optimaliserte vi tykkelse og brytningindeksen for tynnfilm-krystallene silisiumsolceller. Vi undersøkte to dimensjonale nanostrukturer på toppen av tynnfilm c-Si solceller. Vi viste teoretisk at en sylindrisk kuppelstruktur som viser kaotisk bølgedynamikk kan øke effektiviteten inni en absorberende tynn film under. For å opprettholde funnene våre gjennomførte vi full elektromagnetisk simulering i en, to og tre dimensjoner. Simuleringene ble utført med bruk av Norske Infrastruktur for HPC på superdatamaskinene ved Universitetet i Tromsø. Det teoretiske funnet i dette prosjektet gir retningslinjer for solcelleingeniørene i deres forsøk for å skape høy effektive og tynne solceller.

We found some nanostructures on the top of thin film solar cells, that might be better then the random surface structuring. We showed theoretically that chaotic dynamics within a naostructure, that is placed on a crystalline Siliscon solar cell can increase efficiency in an absorbing c-Si thin film. While investigating spheres on the top of thin film solar cells, we learned about resonances that appear inside of nano/microstructures that do not need to have a spherical symmetry. Yhis theoretical finding creates a solid fundament for a new type spectroscopy.

Solar cell technology development and industry are continuously on the lookout for thinner and thus more cost-effective solar cells.Light-management by nanoimprints on top of thin solar cells is expected to provide ultrahigh-efficiency thin cells at low cost. While it has been shown that architectures with spherical and cylindrical nanoimprints can improve the efficiency of solar cells considerably, the physical rational for the absorption enhancement is not completely understood. It is hypothesized that resonant Mie modes inside the nanoimprints couple strongly in the lattice formed by the nanoimprints. Nevertheless, a versatile tool that can predict the efficiency of architectures of solar cells with nanoimprints is not available. Thus, an effective design of solar cells with nanoimprints is not possible. Recently theoretical physicists have introduced a ray model that can effectively optimize microlasers, which are based on strong coupling optical microdisks. It could be shown that the ray model is able to screen design parameters of microlasers for resonant modes. In the field of solar cell technology such a ray model could be a valuable tool to effectively design sizes and materials of nanoimprints and architectures of solar cells. The project at hand suggests development of a ray model for architectures of nanoimprints. The ray model will be used to optimize the design of solar cells with nanoimprints applying two types of material, silicon dioxide and titanium dioxide, and evaluating different architectures. The optimized design will be further validated by applying the finite difference time domain method. Solar cells will be manufactured according to the optimized design and validated experimentally. The project involves experts from solar cell technology and theoretical physics. It addresses a strategic topic in the field of renewable energies, namely the raising of energy efficiency.