Br-2EPT is a self-assembled monolayer (SAM) material that assembles 3,7-dibromo-10H-phenothiazine as the terminal, ethyl chain as the spacer and phosphonic acid as the anchor to the surface of the electrode.
Br-2EPT self-assembled monolayer enables an interface that is energetically well-aligned with the perovskite active layer materials, which minimizes nonradiative interfacial recombination loss by effectively separating charges on the interface. With reduced HOMO energy level induced by bromide groups to minimize the energy-band shift and energy loss, higher VOC can be achieved. The bromine substituents in Br-2EPT form halogen bonds with perovskite and the sulfur atoms in phenothiazine passivate the Lewis acid defects. As a result, Br-2EPT as hole selective contact, hence significantly improves the charge extraction/transport with enhanced device efficiency and long-term stability.
Serving as hole selective contact for organic solar cells and perovskite solar cells, Br-2EPT is an alternative to PEDOT:PSS with superior performance with the convenience of solution deposition at low concentration, i.e. 1 mM.
Typical processing solvents: Anhydrous ethanol (methanol, IPA, IPA/DMF, THF are also superior solvents) Typical concentration: 1 mM (0.465 mg/mL) - 1.0 mg/ml Typical processing procedure: 100 uL of Br-2EPT solution (1mM, 0.465 mg in 1 ml ethanol) is deposited onto the center of the UVO treated FTO or ITO substrate surface and spin-coated for 30 s at the speed of 3000 rpm then annealed at 100 ℃ for 10 minutes (DOI: 10.1002/aenm.202103175)