4PADCB

Small Self-Assembled Monolayer Molecule for High Efficiency Solar Cells

4PADCB, Hole transport or extraction layer for NFA-polymer solar cells and p-i-n perovskite solar cells

Product Information | MSDS | Literature

4PADCB ((4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid, CAS No. 2882156-63-8), also known as CbzNaph, is a self-assembled monolayer (SAM) material with a fused 7H-dibenzo[c,g]carbazole terminal group, a butyl linker and a phosphonic acid group servicing as the anchor to the surface of a substrate. 4PADCB has been engaged as hole transport layer (HTL) to replace PTAA or Spiro-MeOTAD for highly efficient inverted perovskite and all perovskite tandem solar cells. 4PADCB has also been known to promote the stability of such devices.

With a large dipole moment, the helical π-expanded fused carbazole derivative 4PADCB can form ordered and densely packed monolayer on the electrode surface. The electron rich dibenzo[c,g]carbazole terminals, in direct contact with the active layer materials, enlarge the build-in potential and tune the energy level of the active layer materials while simultaneously modulating the perovskite crystallization process and tune the ITO work function by modifying the surface and interface properties through the assembly process.

4PADCB is also known to improve the surface wettability and film coverage, enabling effective hole extraction to suppress the interfacial nonradiative recombination at the interface between the perovskite active layer and the self-assembled hole transport monolayer. As a result, tandem all perovskite solar cells based on a wide band gap (WBG) with an aperture area of 1.044 cm² demonstrates an impressive collective high V_OC of 2.12 V and a fill factor (FF) of 82.6%, giving an outstanding overall PCE of 27.0% (26.4% certified stabilized), a step closer towards scaling up all-perovskite large-area tandem solar cell technology.

Co-solvent strategy, i.e. DMF/IPA has also known to promote the reactivity of the phosphonic acid anchoring group allowing more effective and densely packed 4PADCB onto the electrode surface thus to improve the device performance. DMF/IPA processed 4PADCB device gives device efficiency of 24.98% and improved stability, while IPA alone processed 4PADCB device gives 22.73%.

While comparing with 4PACz, 4PADCB shows a dominant face-on orientation distribution parallel to the electrode surface, promoting the charge transport between the electrode and perovskite active layer, through the hole extracting self-assembled monolayer interface.

Serving as hole selective contact for organic solar cells and perovskite solar cells, 4PADCB is an alternative to PEDOT:PSS with superior performance with the convenience of solution deposition at low concentration, i.e. 1 mM.

Solution Processing Procedure

Typical processing solvents: IPA, IPA/DMF, ethanol
Typical concentration: 1.5 mg/ml, 1.0 mg/ml, 0.5 mg/ml, or 1 mM
Typical processing procedure: 40 uL of 4PADCB solution in IPA (1 mM) is deposited onto the centre of the substrate surface and spin-coated for 30 s at the speed of 3000 rpm. After being annealed for 15 min at 100 ℃, the 4PADCB coated substrate is cooled down to room temperature and washed with IPA (60 uL) by spin-coating the IPA solvent for 30 s at the speed of at 3000 rpm. The now coated and cleaned substrate is then annealed for 5 min at 100 ℃ to afford the 4PADCB self-assembled monolayer on the surface of the substrate (DOI: 10.1002/anie.202213560).

General Information

Product Details

Chemical Structure

MSDS Documentation

4PADCB MSDS Sheet

Literature and Reviews

1. π-Expanded Carbazoles as Hole-Selective Self-Assembled Monolayers for High-Performance Perovskite Solar Cells, W. Jiang et al., Angew. Chem. Int. Ed., 61, e202213560 (2022); DOI: 10.1002/anie.202213560.
   
2. Improving interface quality for 1-cm2 all-perovskite tandem solar cells, R. He et al., Nature 618, 80–86 (2023); DOI: 10.1038/s41586-023-05992-y.
   
3. Optimizing Crystallization in Wide-Bandgap Mixed Halide Perovskites for High-Efficiency Solar Cells, Y. An et al., Adv. Mater., 2306568 (2023); DOI: 10.1002/adma.202306568.
   
4. Self-assembled monolayers as hole-transporting materials for inverted perovskite solar cells, Z. Lan et al., Mol. Syst. Des. Eng., 8, 1440-1455 (2023); DOI: 10.1039/D3ME00144J.
   
5. Compact Hole-Selective Self-Assembled Monolayers Enabled by Disassembling Micelles in Solution for Efficient Perovskite Solar Cells, M. Liu et al., Adv. Mater., 35 (46), 2304415 (2023); DOI: 10.1002/adma.202304415.
   
6. Self-assembled molecules as selective contacts for efficient and stable perovskite solar cells, W. Li et al., Mater. Chem. Front., 8, 681-699 (2024); DOI: 10.1039/D3QM01017A.