Utilizing a Fluorinated Derivative as a Dual-Function Modifier to Improve the Interface Engineering and Long-Term Stability of Inverted Perovskite Solar Cells

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a frequently used hole transport layer (HTL) that often constrains the stability and efficiency of inverted perovskite solar cells (PSCs) because of its hydrophilic properties. In the study, a hydrophobic fluorinated derivative (PM6) was employed as an interfacial modifier for the PEDOT:PSS layer. Modification with PM6 improved the hydrophobicity and work function (WF) of the PEDOT:PSS and mitigated the formation of charge recombination centers (Pb0) on the perovskite surface. The improvement reduced energy losses at the interface by facilitating hole extraction and transport across the PEDOT:PSS/perovskite interface. The PSCs incorporating PM6-modified PEDOT:PSS demonstrated a power conversion efficiency (PCE) of 19.46%, superior to the 18.11% PCE observed for cells utilizing the unmodified PEDOT:PSS. Moreover, the PSCs were subjected to temperature conditions (25 °C) and 15% relative humidity for a period of 360 h. The PM6-modified PEDOT:PSS device maintained 89.75% of its initial PCE. In contrast, the PCE of the pristine device had dropped to 75.06% of its initial PCE. Thus, the PM6-based modification of the PEDOT:PSS/perovskite interface emerges as a viable strategy to bolster the performance and reliability of inverted PSCs.