Title:	Atomistic Modeling of Unconventional Alloys for Solar-Energy Applications
DNr:	NAISS 2024/5-444
Project Type:	NAISS Medium Compute
Principal Investigator:	Clas Persson <claspe@kth.se>
Affiliation:	Kungliga Tekniska högskolan
Duration:	2024-11-01 – 2025-11-01
Classification:	10304 10302 21001
Homepage:	https://www.kth.se/profile/claspe/
Keywords:

Abstract

Our team searches for the optimized materials’ functionalities for solar energy technologies, like next generation solar cells, solar-fuel conversion, light-emitting diodes. Our research also covers energy related research on power battery, steelmaking, and ultrathin film optoelectronics. Lately, we have have had focus on iron, iron-oxides, and high-kappa oxides to support machine learning simulations and measurements within metallurgy. We model, compute, and analyze materials and material structures in order to understand fundamental material physics, support experimentalists in their work, but also to explore new types of material structures. By modeling the material on atomistic and nanoscale, we study the electronic and optical properties, the stability of the materials, impact of defects or alloying, interfaces between materials. With this knowledge we can tailor make materials for an optimized performance of the material systems. In this project we compute and analyze various unconventional alloys and their defects. Special focus is paid to Cu-based solar cell materials as well as to non-traditional semiconductor alloys. Surprisingly, little attention has been paid to understand these unconventional type of materials and alloy structures that are based on traditional semiconductors. In order to develop inorganic photovoltaics based on ultrathin photon-absorbing film the material shall exhibit optimized band-gap energy as well as having a very high absorption coefficient, especially for photons energies in the lower spectrum. We therefore suggest to tailor-make the materials to form direct gap multi-valley band edges. That can typically be achieved by considering alloys with heavy elements that have relatively localized sp-like orbitals or by structural disordering. With such tailored materials, we demonstrate that it is possible to reach a sufficiently high maximum efficiency for film thicknesses of ~100 nm. During the last year we have also studied the wettability of liquid iron on refractory oxides, as well as particle interactions in magnetic fluids. We are combining density-functional theory (DFT) calculations with Casimir-Lifshitz force dispersion forces to analyze fundamental physical interaction. In this research direction, we model how liquid, especially water, interact with solid surfaces, as well as how impurity particles interact in the liquids. Here, our team has expertise in van der Waals interaction within the DFT as well as Casimir-Polder dispersion forces. We explore these alloys and their defects using state-of-the-art methods for accurate calculations. The scientific methods and algorithms are based on the Kohn-Sham method within the DFT, however in this project we employ the GGA and HSE exchange-correlation potentials as well as the post-DFT approach GW method which implies heavy calculations in terms of computational time and memory. When needed, exciton contribution will be included using the Bethe-Salpeter approach. Electronic transport in materials and prototype device will be analyzed by combine atomistic DFT, macroscale models, non-equilibrium Green’s function, and quantum transport simulator.