Functionalized Thienopyrazines on NiOx Film as Self‐Assembled Monolayer for Efficient Tin‐Perovskite Solar Cells Using a Two‐Step Method

Abstract Three functionalized thienopyrazines ( TP s), TP‐MN ( 1 ), TP‐CA ( 2 ), and TPT‐MN ( 3 ) were designed and synthesized as self‐assembled monolayers (SAMs) deposited on the NiOx film for tin‐perovskite solar cells (TPSCs). Thermal, optical, electrochemical, morphological, crystallinity, hole mobility, and charge recombination properties, as well as DFT‐derived energy levels with electrostatic surface potential mapping of these SAMs, have been thoroughly investigated and discussed. The structure of the TP‐MN ( 1 ) single crystal was successfully grown and analyzed to support the uniform SAM produced on the ITO/NiOx substrate. When we used NiOx as HTM in TPSC, the device showed poor performance. To improve the efficiency of TPSC, we utilized a combination of new organic SAMs with NiOx as HTM, the TPSC device exhibited the highest PCE of 7.7 % for TP‐MN ( 1 ). Hence, the designed NiOx /TP‐MN ( 1) acts as a new model system for the development of efficient SAM‐based TPSC. To the best of our knowledge, the combination of organic SAMs with anchoring CN/CN or CN/COOH groups and NiOx as HTM for TPSC has never been reported elsewhere. The TPSC device based on the NiOx /TP‐MN bilayer exhibits great enduring stability for performance, retaining ~80 % of its original value for shelf storage over 4000 h.