Synergistic Engineering of the Conductivity and Surface Properties of PEDOT:PSS-Based HTLs for Inverted Tin Perovskite Solar Cells to Achieve Efficiency over 10.

A new simple environmentally benign water-soluble zwitterion, sulfamic acid (SA), was used as a multifunctional additive to tune the properties of PEDOT:PSS-based hole transporting layer (HTL). A layer of PEDOT:PSS was inserted in-between the ITO electrode and SA-modified PEDOT:PSS to form a pseudo bi-layered PS/SA@PS HTL to protect the ITO electrode from damage by more acidic SA@PS. Inverted tin-based perovskite solar cells based on the pseudo bi-layered PS/SA@PS HTLs achieved the highest efficiency of 10.