Since the first report was published by Miyasaka et al.,1) perovskite solar cells have been drastically developed for 10 years. One of the main bottlenecks towards large-scale production is in the hole transport layer, though many researchers have challenged to stabilize and upscale perovskite solar cell for a practical use. Some conventional hole transport materials, Spiro-OMeTAD and PTAA, require expensive material cost and are destabilized due to a necessary dopant for a carrier transport.
Recently, Getautis, Albrecht et al. developed some hole selective self-assemble monolayer (SAM) forming agents, 2PACz [C3663], MeO-2PACz [D5798] and Me-4PACz [M3359], for high performance perovskite solar cell. 2PACz, MeO-2PACz and Me-4PACz can form a monolayer on a metal oxide surface anchored by the phosphonic acid moiety. These materials are useful for a tandem solar cell because it makes a conformal coverage on rough textures. A perovskite solar cell using the SAM hole transport layer can realize more than 20% efficiency without any dopants, and very cost effective because extremely low material consumption. Organic thin film solar cell (OPV) using 2PACz showed 18.03% power conversion efficiency that is better performance than those of using the existing PEDOT:PSS. Perovskite-Silicon tandem solar cell using Me-4PACz as a hole contact material realized 29.15% efficiency (Table 1).
- Enable efficient, versatile and stable solar cell devices without additives, interlayers or dopants
- Self-assembly leads to conformal coverage of oxide surfaces (including textured)
- Simple, scalable and extremely cost-effective processing
Method 1: Dip coating
suitable for large-area coating and textured substrates
Method 2: Spin coating
suitable for fast research & optimization
- The SAM forming agents can be processed within wide processing windows with higher reproducibility than current standard hole transport materials (like PTAA). The substrates (e.g. ITO) have to be clean and activated by, for example, UV-Ozone treatment.
- The SAM forming agent powders were usually dissolved in ethanol or isopropanol (1 mmol/L ≈ 0.3 mg/mL), MeO-2PACz powder was stored in air, while 2PACz and Me-4PACz were stored in a N2-filled glovebox.
- 1) Conformal monolayer contacts with lossless interfaces for perovskite single junction and monolithic tandem solar cells
- 2) Co-Evaporated p-i-n Perovskite Solar Cells beyond 20% Efficiency: Impact of Substrate Temperature and Hole-Transport Layer
- 3) Monolithic perovskite/silicon tandem solar cell with >29% efficiency by enhanced hole extraction
- A. Al-Ashouri, E. Köhnen, B. Li, A. Magomedov, H. Hempel, Pietro Caprioglio, J. A. Márquez, A. B. M. Vilches, E. Kasparavicius, J. A. Smith, N. Phung, D. Menzel, M. Grischek, L. Kegelmann, D. Skroblin, C. Gollwitzer, T. Malinauskas, M. Jošt, G. Matič, B. Rech, R. Schlatmann, M. Topič, L. Korte, A. Abate, B. Stannowski, D. Neher, M. Stolterfoht, T. Unold, V. Getautis, S. Albrecht, Science 2020, 370, 1300.
- 4) Self-Assembled Monolayer Enables Hole Transport Layer-Free Organic Solar Cells with 18% Efficiency and Improved Operational Stability
- 5) 20.8% Slot-Die Coated MAPbI3 Perovskite Solar Cells by Optimal DMSO-Content and Age of 2-ME Based Precursor Inks
- 6) NREL solar cell efficiency chart