Synthesis and physical characterization of atomically thin FeS2

Background:

Thin-film solar cells, due to reduced materials cost and promising efficiency, gain momentum in large-scale deployment of photovoltaic technology for solar-to-electric power conversion with a potential to meet the grid parity with that of conventional fossil fuel based energy production. The champion materials for thin-film solar cells are crystalline silicon (c-Si), CdTe, and CuIn1-xGaxSe2 (CIGS). However, rareness and toxicity of Cd, Te, In and Se limit their widespread application. In pursuit of alternative materials, iron pyrite (FeS2) is an interesting alternative with comparable high absorption of CdTe and CIGS, and with high abundance, low-toxicity, as well as proven stability over geological time scales. United States geological survey studies has ranked FeS2 as the best among the 23 inorganic photovoltaic materials based on annual electricity production potential.

Despite these impressive properties and ranking, solar-to-electric power conversion efficiency of FeS2 is < 3% because of disappointingly low open circuit voltage (VOC < 0.2 V, ~ only 20 % of bandgap). If the efficiency can improve to 10%, the estimated production cost of electricity with FeS2 can fall as low as < 0.000002 ¢/W. Apparently, a 10% efficiency look far beyond the reality, however, it is argued that if the VOC can increase to 500 mV, we can reach a conversion efficiency of ~ 20%. Therefore, intensive research is needed to improve the VOC of FeS2 based solar cell.

In this regard, this project aims to synthesize ultrathin 2D FeS2, and characterize its photophysical properties for fundamental investigations and for future solar cell applications.

Project description:

Exfoliation, intercalation, and liquid metal reaction will be exercised to figure out a scalable synthesis route for atomically thin FeS2. State-of-the art characterization techniques will be employed to understand its (i) photophysical properties using UV-Vis spectroscopy, (ii) vibrational properties using confocal Raman Spectroscopy, (iii) morphology using TEM, SEM and AFM, (iv) chemical states using EDX, XPS, and FTIR.

The information obtained from this project will be used to engineering the pyrite phase of FeS2 for fabrication of high efficiency extremely thin film solar cells.

The proposed work will be performed at the division of Solid State Physics, Department of Engineering Sciences, Uppsala University. The suitable candidate should have, at least, basic knowledge on materials science, solid-state physics, and materials chemistry. Additionally, some knowledge in nanomaterials synthesis and understanding of physical characterization technique is a plus but not mandatory. Good knowledge of physics and/or chemistry is mandatory.

For question and enquiries, please contact: Dr Mohammad Ziaur Rahman (e-mail: mohammad.rahman@angstrom.uu.se; Phone# +46701679705)