A Simple Perylene Derivative as a Solution-Processable Cathode Interlayer for Perovskite Solar Cells with Enhanced Efficiency and Stability

A simple alcohol-soluble perylene derivative (i.e., tetramethylammonium salt of perylene-3,4,9,10-tetracarboxylic acid; TMA-PTC) was prepared and applied as a cathode interlayer (CIL) to modify the PC₆₁BM/Ag interface in planar p–i–n perovskite solar cells (PeSCs). As a result, the power conversion efficiency (PCE) of the TMA-PTC-based PeSCs is ca. 30% higher than that of the devices without CIL. It was revealed that the enhancement in PCE might be attributed to the improved electron-transporting and hole-blocking properties of the PC₆₁BM/TMA-PTC/Ag interfaces. Moreover, the TMA-PTC devices show remarkably higher stability than those without CIL probably due to the suppressed corrosion of perovskite on Ag cathode. Our findings thus demonstrate a multifunctional and solution-processable CIL that may be a promising block for the fabrication of low-cost, high-efficiency and stable planar p–i–n PeSCs

WO_<i>x</i>@PEDOT Core–Shell Nanorods: Hybrid Hole-Transporting Materials for Efficient and Stable Perovskite Solar Cells

PEDOT-coated WO_<i>x</i> nanorodes (NRs) were prepared for the first time by simply stirring WO_<i>x</i> nanowires (NWs) with 3,4-ethylenedioxythiophene (EDOT) in aqueous solution. A series of spectroscopic characterizations indicate that the polymerization of EDOT occurrs not only on the surface but also along the [010] planes of WO_<i>x</i> NW, resulting in the truncation of long WO_<i>x</i> NW to produce WO_<i>x</i>@PEDOT NRs with abundant oxygen vacancies. Furthermore, WO_<i>x</i>@PEDOT NRs were used to prepare a hole transport layer (HTL) in planar p–i–n perovskite solar cells (PeSCs). The WO_<i>x</i>@PEDOT-based devices yielded a comparable average power conversion efficiency (PCE) of 12.89% with improved open-circuit voltage (<i>V</i>_OC) and fill factor (FF) but lower short-circuit current density (<i>J</i>_SC), as compared to the devices with conventional PEDOT:PSS (12.88%). The observed device performance is mainly attributed to the better perovskite texture on the WO_<i>x</i>@PEDOT HTL, improved energy alignment, and suppressed charge recombination at the WO_<i>x</i>@PEDOT/perovskite interface as well as lower charge conductivity of the WO_<i>x</i>@PEDOT HTL. In addition, the PeSCs based on WO_<i>x</i>@PEDOT-doped PEDOT:PSS showed remarkably improved PCEs up to 14.73%, which may be ascrible to the combined merit of WO_<i>x</i>@PEDOT NRs and PEDOT:PSS. More impressively, benefiting from the inherent neutral nature of WO_<i>x</i>@PEDOT NRs, WO_<i>x</i>@PEDOT-based devices exhibited obviously improved stability compared to that with PEDOT:PSS HTL. These results thus demonstrate a path toward the development of new hybrid nanostructures for efficient and stable PeSCs