Cu₂(Thiourea)Br₂ Complex as a Multifunctional Interfacial Layer for Reproducible PTAA-Based p-i-n Perovskite Solar Cells

Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA) is one of the most efficient hole transport materials for p-i-n structured perovskite solar cells (PSCs). However, the hydrophobicity of PTAA causes wettability problems and is thereby associated with low yield and poor reproducibility. Herein, a new strategy for improving the perovskite precursor wettability on PTAA is developed. A Cu-2(Thiourea)Br-2 complex interfacial layer is introduced on the PTAA, improving the coverage of perovskite precursors and thereby the perovskite film. Partially dissolved Cu-2(Thiourea)Br-2 in the perovskite absorber further enhances band alignment and carrier extraction between layers. With the addition of Cu-2(Thiourea)Br-2 layer on nondoped PTAA, PSCs in p-i-n structure with a bandgap of 1.63 eV have achieved over 21% efficiency both on 0.1 and 1.0 cm(2) sized devices with a significantly improved yield and reproducibility. Unencapsulated devices retain 100% of their initial efficiency after 2000 h at 65 degrees C.