Evaporated Self Assembled Monolayer (SAM) Hole Transport Layers for Scalable Perovskite Solar Cells

misc
Jan 01, 2025
authors
Vollbrecht, J. and Barnscheidt, V. and Clausing, R. and Löhr, J. and Mettner, L. and Neuba, A. and Raugewitz, A. and Strey, J. and Peibst, R.
featured_in
European Photovoltaic Solar Energy Conference and Exhibition (EUPVSEC), Bilbao, Spain

abstract

This study investigates the feasibility of using evaporated organic hole-transport layers (HTLs) based on self-assembled monolayers (SAMs) in perovskite (Pk) single-junction solar cells. A major challenge lies in the degradation of SAM materials during thermal evaporation (TE), which can reduce device performance. To address this, we analyzed the impact of thermal exposure during deposition, comparing vacuum-evaporated HTLs to spin-coated HTLs – the latter being a lab-scale technique that is not suitable for industrial upscaling. Results reveal that repeated TE cycles lead to performance losses, likely due to molecular decomposition of the SAM material. By reducing the evaporation rate and minimizing the HTL thickness to as little as 1 nm, thermal exposure was significantly reduced. Optimized thermal evaporation parameters resulted in metal-halide perovskite solar cells with cell parameters comparable to, or even exceeding that of spin-coated reference cells. These findings provide critical insights for scaling SAM HTL deposition processes to industrially viable methods, enabling efficient fabrication of Pk solar cells on large areas. They may also enable conformal coverage on textured silicon surfaces, a key requirement for Pk-silicon tandem systems.