Perovskite bulk and surface modifications for highly efficient and stable perovskite-silicon tandem solar cells

Solar photovoltaics (PV) is dominating worldwide energy capacity additions. At the same time, new technologies are being developed to overcome the power conversion efficiency (PCE) limits of silicon PV and to find applications in new markets. Tandem solar cells offer a way to higher PCEs by stacking cells with different bandgaps on top of each other, which results in a more optimal utilization of the solar spectrum.

Perovskite PV is currently the fastest growing and the most promising emerging thin-film PV technology. Research on perovskite-silicon (Pk-Si) tandem cell technology has led so far to a 33.7% PCE at lab scale, much beyond the Auger limit of Si solar cells. However, several key challenges remain unsolved for this technology, long-term operational stability being one of them. In general, a higher optoelectronic ‘quality’ of the perovskite films will result in better performing solar cells.

At imec, we are developing a wide bandgap (1.65-1.70 eV) perovskite material deposited using a 2-step hybrid vapor-solution approach with great potential for the upscaling of tandem technologies. In this master thesis/internship project, two common strategies to improve the performance and stability of perovskite (top) cells will be explored, namely the use of additives (salts and other relatively small molecules with different functional groups) in the precursor materials, and the use of post-deposition passivation treatments targeting the perovskite film’s surface defects and grain boundaries.

Perovskite thin films and solar cells will be fabricated using sputtering, evaporation, and solution coating tools. The samples’ electrical and optoelectronic properties will be systematically characterized to investigate the impact of the different treatments on the films’ crystallization and defect passivation (bulk, grain boundaries, and interfaces). Characterization techniques: current-voltage measurements (IV), photoluminescence (PL), electroluminescence (EL), scanning electron microscopy (SEM), X-ray diffraction (XRD), etc.

With this thesis we aim to achieve reproducible, highly-efficient and highly-stable perovskite top cells for textured Pk-Si tandem cells. The work will generate a deeper understanding of the charge carrier recombination mechanisms and their adequate passivation strategies.
The work will be conducted at our EnergyVille Thin-Film PV lab in Genk, Belgium. 

Type of Project: Thesis; Internship; Combination of internship and thesis 

Master's degree: Master of Engineering Science; Master of Science; Master of Engineering Technology 

Master program: Chemistry/Chemical Engineering; Electrotechnics/Electrical Engineering; Energy; Materials Engineering; Nanoscience & Nanotechnology; Physics; Other 

Duration: 6 - 12 months 

Supervisor: Jef Poortmans (EE, Nano, Energy) 

For more information or application, please contact Yinghuan Kuang (yinghuan.kuang@imec.be) and Cristian Villalobos Meza (cristian.villalobosmeza@imec.be)

Imec allowance will be provided for students studying at a non-Belgian university.