First-principles calculations of electronic and optical properties of disordered and amorphous CuI-based ternary alloys

• Applicant: Professorin Dr. Silvana Botti
• Subject Area: Theoretical Condensed Matter Physics
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 403159832

We propose to perform predictive calculations of electronic band structures, transport coefficients and optical spectra of transparent semiconducting copper-halide ternary compounds and alloys, using and further developing the best available theoretical and computational approaches for solids. In the first period of the research unit FOR2857 we targeted the optimization of conductivity and transparency of p-type CuI. After a thorough study of the zincblende phase γ-CuI, we investigated other crystalline phases, different stoichiometries, defects and substitutional doping. We predicted and characterized novel stable compounds from the calculation of phase diagrams of ternary systems including Cu, I and another element of the periodic table up to Bi. Our main objective was and remains to propose ways to enhance hole mobility and concentration without compromising transparency. In the second funding period we want to build upon present results. First, we will enlarge the search space, moving the focus from CuI to CuI-based ternary crystals. Our plan includes: (i) high-throughput engineering of dopants for CuI-based ternaries that we have pre-selected as promising p-type transparent semiconductors; (ii) deep analysis of the effect of Cu vacancies and modifications of I coordination on the electronic properties of CuI-based crystals; (iii) computational characterization of amorphous ternary films. Second, we will push forward the thermodynamic analysis of the ternary phase diagrams to include entropic terms, and therefore account for effects of disorder on thermodynamic stability and electronic properties of CuI-based alloys. As usual, we will filter out systems that do not satisfy requirements related to the targeted application. The best candidate systems will instead be passed forward for accurate electronic characterization beyond standard density-functional theory (DFT), applying new approximations for DFT and time-dependent DFT, that we have derived from many-body perturbation theory. At all stages of our computational investigation, a continuous transfer of relevant information to the partners of FOR2857 will allow to accelerate the work and maximize its impact. The large amount of data collected during the whole duration of the project will be analyzed using machine learning to extract design rules for p-type transparent conductors.

• DFG Programme: Research Units
• Subproject of: FOR 2857: Copper Iodide as Multifunctional Semiconductor