Van der Waals colloquium by dr. Monica Morales Masis from the University of Twente (Netherlands) on "Development of New Optoelectronic Thin Film Materials for Low-Cost and Efficient Solar Cells". Monica’s lab studies transparent conducting oxides, hybrid and new synthetic materials for the development and understanding of functional optoelectronic materials and thin films.

Abstract: Photovoltaics (PV) is placed at the heart of the energy transition and thin-film PV is a key technology aiming at lower cost and lower environmental impact compared to e.g. crystalline silicon PV. While several fundamental and technological challenges have been tackled in the field, the development of new sustainable semiconductors for low-cost and efficient solar cells remains an open challenge. Materials science plays a critical role in addressing this challenge, from the discovery and synthesis of new materials to characterization and modeling.

In this presentation, we will explore the development, growth and understanding of new semiconductor materials for solar cells, including photoactive light-absorbers and transparent electrodes with either n- or p-type conductivity.

First, we will show how understanding of growth from the atomic to the macroscale leads to enhanced electron mobility in transparent conducting oxides (TCO), and with this achieve optimum broadband transparent n-type semiconductors with conductivity close to a metal. Second, we will discuss how material design and controlled synthesis have enabled us to experimentally demonstrate transparent p-type conductive materials, which have been a major and longstanding challenge in optoelectronic materials. Exploring beyond oxides and moving to halide and chalco-halide systems, semiconductors with a disperse valence band can be fabricated. Disperse valence band semiconductors present improved hole mobility, contrary to the case of oxide semiconductors.

Finally, we will present recent developments in a versatile vacuum- and laser-based deposition method for controlling the fabrication of hybrid organic-inorganic materials, using the example of hybrid metal halide perovskites. We will demonstrate how this method leads to the stabilization of photoactive phases and the creation of high-quality thin films, which can then be integrated as absorbers into highly efficient solar cell devices.

In summary, the presentation will highlight how controlled synthesis, material design and integration of new materials into proof-of-concept devices make a significant contribution to the emerging generation of efficient and sustainable solar cell devices.

The Joan van der Waals colloquium is an ongoing bi-weekly lecture series, organized by LION. As all speakers are instructed to give an accessible lecture for everyone, these lectures aid in getting a broader view of physics. Each colloquium is preceded by an opening act: a PhD student or postdoc from LION and a different field than the invited speaker, to give a 10-min presentation. After the colloquium, there is a chance to meet your colleagues and participate in discussions at the borrel. More information can be found here.