Bulk and interface passivation for solution-vapor hybrid and vacuum processed single and multijunction perovskite solar cells

In recent years, perovskite solar cells (PSCs) have been under the spotlight as a promising candidate for next-generation photovoltaic (PV) technology, either in a format of single junction solar cell or in combination with matured silicon PV technology forming a multijunction device. The certified power conversion efficiency (PCE) of single junction PSCs has reached 26.1%. The PCE has been further boosted to 33.7% for perovskite/Si tandem cell with more efficient usage of the incident photons.

Commonly, solution processing such as spin coating is widely used for deposition of the perovskite photoactive layer. However, it is rather challenging to grow compact perovskite film with high quality on substrates with roughness such as textured Si with feature sizes of a few microns. In this regard, there is nowadays a growing interest to explore the solution-vapor sequential hybrid approach, and also vacuum thermal evaporation. For the latter, it can be all sources evaporated simultaneously, or in a sequential method. Such thermal evaporation based approach enables conformal coating of perovskites on rough substrates for multijunction solar cell application.

This PhD project will focus on bulk and surface modifications of perovskites via the usage of additives and interlayers. The study focuses initially on the development of a certain perovskite composition (CsxFA1-xPbI3-yBry) by the solution-vapor hybrid approach. Depending on the progress, it will be expanded to fully thermal evaporation. The second objective is the fundamental understanding of the several defects that are present within the developed perovskite layer (in the bulk, at the grain boundaries and surfaces). Based on such understanding, additives and interlayers will be explored to investigate their influence on passivating the defects in the bulk and at both interfaces with adjacent charge transport layers. The most promising candidates will be selected in the end. The third objective is to successfully integrate the selected additive(s) and interlayers in the processing of PSCs single junction solar cells and minimodules. The application of the developed passivation strategies will also be implemented in perovskite/Si dual junctions and perovskite/perovskite/Si triple junction devices, with close collaboration with other colleagues in the group working on the multijunction devices.

The candidate will fabricate PSCs, test their stability under intrinsic stress factors (thermal, light soaking under elevated temperature, etc.) and improve their stability by modifying the bulk and the interfaces. The candidate will perform opto-electronic characterization on materials and devices (dark and light JV scans, photo- and electro-luminescence, impedance spectroscopy ...). Involvement in the implementation of the selected passivation strategies in dual and triple junction devices is also expected.

The project will be conducted in an interdisciplinary and multicultural team of highly skilled scientists and engineers that work towards the next generation of PV technology. The research will be developed in the newly built laboratories at EnergyVille, Genk, working in one of the world’s premier research centers in nanotechnology.

Required background: Chemistry, Physics, Material Science and Engineering

Type of work: 70% experimental, 15% modeling, 15% literature

Supervisor: Bart Vermang (UHasselt)

Co-supervisor: Jef Poortmans

Daily advisor: Yinghuan Kuang

The reference code for this position is 2024-098. Mention this reference code on your application form.