WOx@PEDOT Core–Shell Nanorods: Hybrid Hole-Transporting Materials for Efficient and Stable Perovskite Solar Cells
journal contributionposted on 04.04.2018, 00:00 by Ping Liu, Chen Wang, Dongying Zhou, Quan Yuan, Yu Wang, Yao Hu, Dongwei Han, Lai Feng
PEDOT-coated WOx nanorodes (NRs) were prepared for the first time by simply stirring WOx 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  planes of WOx NW, resulting in the truncation of long WOx NW to produce WOx@PEDOT NRs with abundant oxygen vacancies. Furthermore, WOx@PEDOT NRs were used to prepare a hole transport layer (HTL) in planar p–i–n perovskite solar cells (PeSCs). The WOx@PEDOT-based devices yielded a comparable average power conversion efficiency (PCE) of 12.89% with improved open-circuit voltage (VOC) and fill factor (FF) but lower short-circuit current density (JSC), 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 WOx@PEDOT HTL, improved energy alignment, and suppressed charge recombination at the WOx@PEDOT/perovskite interface as well as lower charge conductivity of the WOx@PEDOT HTL. In addition, the PeSCs based on WOx@PEDOT-doped PEDOT:PSS showed remarkably improved PCEs up to 14.73%, which may be ascrible to the combined merit of WOx@PEDOT NRs and PEDOT:PSS. More impressively, benefiting from the inherent neutral nature of WOx@PEDOT NRs, WOx@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.