Since the first report was published by Miyasaka et al.,1) perovskite solar cells have been drastically developed for 10 years.2) 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] and MeO-2PACz [D5798], for high performance perovskite solar cell. 2PACz and MeO-2PACz 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.3)
- Enable efficient, versatile and stable p-i-n perovskite solar cell devices (> 21 % PCE without additives, interlayers or dopants)
- Self-assembly leads to conformal coverage of oxide surfaces (including textured)
- Simple, scalable and extremely cost-effective processing
Stabilized power conversion efficiencies with self-assembled monolayer (SAM):
(CsMAFA = Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3, MAFA = MA0.05 FA0.95Pb(I0.95Br0.05)3,
Cs = cesium, MA = methylammonium, FA = formamidinium, CIGSe = copper indium gallium selenide)
*These data are taken from Reference3).
Method 1: Dip coating
suitable for large-area coating and textured substrates
Method 2: Spin coating
suitable for fast research & optimization
*Depending on the used concentration, the minimum needed dipping time can vary from minutes to hours. As a starting point: e.g., 0.1 mmol/L and 1 h dipping at room temperature.
- The SAMs 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 powders were usually dissolved in ethanol or isopropanol (1 mmol/L = 0.3 mg/mL), MeO-2PACz powder was stored in air, while 2PACz was stored in a N2-filled glovebox.
- 1) Organometal halide perovskites as visible-light sensitizers for photovoltaic cells
- 2) NREL solar cell efficiency chart
- 3) Conformal monolayer contacts with lossless interfaces for perovskite single junction and monolithic tandem solar cells