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In recent years, a wide variety of self-assembled monolayer (SAM) formation reagents, including the PACz series used as hole-selective layers, have been widely used in perovskite solar cell research.
We have the PACz series, 3PATAT-C3, 3CATAT-C3, PANDI, etc., available in our catalog. Please feel free to inquire about bulk supply options.
Table of Contents
PACz series
The PACz series was developed by Getautis and Albrecht et al. as a hole-selective layer suitable for p-i-n ("inverted") architecture perovskite solar cells.1) Hole-selective self-assembled monolayers (SAMs) can be formed on transparent electrodes such as ITO owing to phosphonic acid anchors of PACzs that form covalent bonds on the metal oxide surface. Both spin-coating and dip-coating methods are effective for fabricating PACz SAMs. PACz SAMs have been reported to achieve effective hole extraction and small density of trap states, and thus achieve higher power conversion efficiency (PCE) and stability compared to cells using PTAA (= poly[bis(4-phenyl)(2,4,6-trime-thylphenyl)amine]), which is commonly used in p-i-n type cells. PACzs have also formed SAMs on a compound semiconductor, CIGSe, indicating compatibility with tandem cells. Furthermore, studies have shown that PACzs contribute to improved PCE and stability in organic photovoltaics,2,3) and can be applied as an electron selective layer on a crystalline silicon (c-Si) solar cell.4) We provide 2PACz series including 2PACz, MeO-2PACz, Me-2PACz, Br-2PACz, Cl-2PACz, F-2PACz, and I-2PACz, and 4PACz series including 4PACz, MeO-4PACz, Me-4PACz, and Br-4PACz.
Products
The 2PACz and 4PACz series are covered by a joint patent pending (PCT/EP2019/060586) of Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Germany and Kaunas University of Technology, Lithuania. TCI has been granted the right to manufacture and sell these materials.
Materials Processing of PACz series
Method 1: Dip coating
suitable for large-area coating and textured substrates
Method 2: Spin coating
suitable for fast research and optimization
*The minimum needed dipping time can vary from minutes to hours. After some further testing with 2PACz, researchers found more reproducible results with rather 0.5 mmol/L and 5 minutes dipping. Note that optimal concentration and dipping time may vary depending on the used substrate oxide and pre-treatment.
- 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.
Product Spotlight Page
3PATAT-C3 and 3CATAT-C3
3PATAT-C3 is a hole-collecting SAM forming material developed by Wakamiya et al.5) Its planar π-structure and three phosphonic acid anchor groups enable the formation of SAMs oriented face-on to the substrate, which is expected to result in efficient charge collection.
Furthermore, Wakamiya et al. also reported 3CATAT-C3, in which the anchor groups are carboxylic acids.6) Because some of the carboxylic acid groups do not bind to ITO and remain exposed at the surface of the monolayer, the 3CATAT-C3 monolayer is more hydrophilic and exhibits higher wettability than the 3PATAT-C3 monolayer. Moreover, 3CATAT-C3 is suitable for the co-deposition method, in which it is incorporated into the perovskite precursor solution and deposited simultaneously with the perovskite layer, showing device performance comparable to that of the layer-by-layer method.
Products
3PATAT-C3 and 3CATAT-C3 are commercialized under the instruction of Professor Atsushi Wakamiya, and under an invention license by EneCoat Technologies Co., Ltd.
Product Spotlight Pages
PANDI
Musiienko, Malinauskas, Azmi, and De Wolf et al. developed an electron-selective SAM molecule named PANDI for n-i-p ("direct") architecture perovskite solar cells.6) Owing to its high electric dipole moment, PANDI has been reported to facilitate efficient charge extraction and suppress non-radiative recombination on the interface. PANDI can replace conventional metal oxide electron transport layer such as titanium(IV) oxide (TiO2) and Tin(IV) oxide (SnO2). PANDI can form an electron-selective layer by annealing at 100 °C, which is advantageous for fabrication on flexible substrates.
Product
The PANDI is covered by a patent pending (US Patent Application No. 18/416,458) for which Kaunas University of Technology (KTU), Lithuania, and King Abdullah University of Science and Technology (KAUST), Saudi Arabia, are co-applicants. TCI has been granted the right to manufacture and sell this material.
Materials Processing of PANDI 7)
- Dissolve PANDI in chlorobenzene (0.5-1.0 mg/mL).
- Spin-coat the solution onto ITO glass (5000 rpm, 30 seconds).
- Anneal the substrate at 100°C for 10 minutes.
- Wash the formed SAM layer with chlorobenzene.
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BrNH3-4PACz
BrNH3-4PACz is a hole‑selective layer material developed by S. De Wolf et al. for narrow‑bandgap perovskites.8) In addition to its favorable energy level alignment with narrow‑bandgap Pb–Sn perovskites, the ammonium bromide moiety passivates the perovskite interface and contributes to the regulation of the perovskite film crystallization.
Product
The PACz series including BrNH3-4PACz are covered by a joint patent pending (PCT/EP2019/060586) of Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Germany and Kaunas University of Technology, Lithuania. TCI has been granted the right to manufacture and sell these materials.
Product Spotlight Page
Ph-2PACz
Ph-2PACz, developed by Cheng, Ding, and Ho-Baillie et al., is a hole-selective layer material suitable for wide-bandgap perovskites.9) Ph-2PACz has demonstrated better PCE than PTAA and 2PACz in wide-bandgap (1.67 eV) perovskite solar cells (Cs0.15FA0.65MA0.2Pb(I0.8Br0.2)3). This improvement is attributed to the small energy offset between the highest occupied molecular orbital (HOMO) level of Ph-2PACz and the valence band maximum (VBM) of the perovskite, along with its favorable wettability, which enhances perovskite film quality. Furthermore, its effectiveness has also been demonstrated in tandem solar cells.
Product
Related Product Category Pages
Product Brochures
Hole-selective SAM Forming Agent Contributing to Improved Performance of OPVs: Cl-2PACz (PDF file)
SAM Formation Reagent with Face-on Orientation to Substrate Surface: 3PATAT-C3 (PDF file)
SAM Formation Reagent with Three Carboxylic Acid Moieties as Anchors: 3CATAT-C3 (PDF file)
n-Type SAM Forming Agent Enabling Efficient Perovskite Solar Cell: PANDI (PDF file)
SAM-Forming Agent for Efficient NBG-Type Perovskite Solar Cells: BrNH3-4PACz (PDF file)
References
- 1) Conformal monolayer contacts with lossless interfaces for perovskite single junction and monolithic tandem solar cells
- 2) 18.4% Organic Solar Cells Using a High Ionization Energy Self-Assembled Monolayer as Hole-Extraction Interlayer
- 3) 18.9% Efficient Organic Solar Cells Based on n-Doped Bulk-Heterojunction and Halogen-Substituted Self-Assembled Monolayers as Hole Extracting Interlayers
- 4) Efficient Silicon Solar Cells through Organic Self-Assembled Monolayers as Electron Selective Contacts
- 5) Tripodal Triazatruxene Derivative as a Face-On Oriented Hole-Collecting Monolayer for Efficient and Stable Inverted Perovskite Solar Cells
- 6) Molecular Design of Hole-Collecting Materials for Co-Deposition Processed Perovskite Solar Cells: A Tripodal Triazatruxene Derivative with Carboxylic Acid Groups
- 7) Nonfullerene Self-Assembled Monolayers As Electron-SelectiveContacts for n-i-p Perovskite Solar Cells Inverted Perovskite Solar Cells
- 8) Efficient Narrow Bandgap Pb–Sn Perovskite Solar Cells Through Self-Assembled Hole Transport Layer with Ionic Head
- 9) Molecular Engineering of Hole-Selective Layer for High Band Gap Perovskites for Highly Efficient and Stable Perovskite–Silicon Tandem Solar Cells
