Improving the Performance and Stability of Inverted Perovskite Solar Cell Modules by Cathode Interface Engineering

Perovskite solar cells (PSCs) represent a highly promising photovoltaic technology wherein a low -work function metal cathode is essential for efficient electron collection. The effectiveness of PSCs is significantly enhanced by a well -designed cathode interface layer (CIL). Characterized by their simple structure and impressive modification capabilities, small -molecule CILs hold considerable commercial potential for advancing the performance of PSCs. Herein, we synthesized a conjugated small -molecule CIL, named FY1, for modulating the cathode interface of inverted PSCs to enhance the power conversion efficiency (PCE) and long-term stability. FY1 not only optimized the molecule/metal contact to reduce traps but also uniformly improved the efficiency and speed of extracting photogenerated electrons, facilitating their effective extraction at the cathode interface. FY1 modification reduced the work function of Ag, subsequently lowering the energy barrier for electron transfer from the electron transport layer to the external cathode metal. By employing FY1 as a CIL, a record -high PCE of 23.72 % and a fill factor of 82.3 % were achieved in inverted PSCs. Furthermore, FY1 modification increased the PCE of PSC modules with an active area of 14 cm 2 to 21.8 %; after continuous illumination for 850 h, it retained approximately 98.5 % of the initial efficiency. These findings show that FY1 can assist in unlocking the full potential of this emerging photovoltaic technology.