Cl-2PACz ([2-(3,6-dichloro-9H-carbazol-9-yl)ethyl]phosphonic acid) is a halogenated self-assembled monolayer (SAM) material with a 3,6-dichloro-9H-carbazole terminal group, a phosphonic acid anchor and an ethyl spacer between the hole transporting terminal and the anchor to the surface of the electrode. Cl-2PACz has been proven an effective hole-selective contact to replace PEDOT:PSS on ITO for all organic non-fullerene polymer solar cells.

With strong electron-withdrawing capability and empty 3d orbits, chlorine atom intends to form strong noncovalent interactions, such as Cl···S and Cl···π interactions. The synergistic effect of electronegativity, together with the empty 3d orbits of chlorine atoms, lead to increased intramolecular and intermolecular interactions, resulting better charge mobilities on the interface.

Bulk heterojunction (BHJ) solar cells utilizing PEDOT:PSS free ITO/Cl-2PACz anodes with PM6:PM7-Si as the binary polymer donors, BTP-eC9 as the non-fullerene acceptor demonstrated a maximum PCE of 18.5%. This was a great enhancement from that of PEDOT:PSS coated electrode (17.5%). It was also observed that OPV solar cells with Cl-2PACz as the interlayer showed better device stability under continuous illumination with white light than those with PEDOT:PSS as the hole transport layer. The device performance improvements with the interlayer of Cl-2PACz sandwiched between the anode and the photoactive layer are from a combined result of increased charge mobilities and supressed charge recombination, reduced resistance at the interface and longer carrier lifetime.

Serving as hole selective contact for organic solar cells and perovskite solar cells, Cl-2PACz 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: Anhydrous ethanol (IPA, IPA/DMF are also superior solvents)
Typical concentration: 0.3 - 1.0 mg/ml
Typical processing procedure: Cl-2PACz is dissolved in anhydrous ethanol at a concentration of 0.3 mg/ml. The solution is applied directly onto the ITO substrate for 20 s followed by spin-coating the solution for 30 s at 3000 rpm. The resulting Cl-2PACz coated substrate is then cooled to toom temperature after being annealed for 4 min at 50 - 100 ℃, followed by being washed twice with the same Cl-2PACz solution (0.3 mg/mL) (DOI: 10.1002/aenm.202202503).

General Information

Product Details

Chemical Structure

Cl-2PACz chemical structure