Perovskite/Hole Transport Layer Interfacial Engineering with Substoichiometric Tungsten Oxide Rich in Oxygen Vacancies to Boost the Photovoltaic Performance of Perovskite Solar Cells

The collaborative strategy of optical design and charge transport dynamics optimization can provide double guarantee to achieve high‐efficient planar perovskite solar cells (PSCs). Herein, WO 3− X nanorods with tunable localized surface plasmon resonance (LSPR) effect are introduced at the interface between perovskite and hole transport layer (HTL) via antisolvent method during the preparation of perovskite films. The photocurrent of WO 3− X nanorods‐based devices significantly increases due to the extension of absorption region caused by LSPR effect. The charge transfer at the perovskite/HTL interface is also accelerated due to the electromagnetic near‐field enhancement via the LSPR effect. The synchronized improvement in photocurrent and charge transfer by WO 3− X nanorods leads to a power conversion efficiency of 21.14% in MAPbI 3 ‐based PSCs. This work not only provides an effective approach to enhance the photovoltaic performance of PSCs, but also demonstrates the potential application of inorganic oxide semiconductors with LSPR in other optoelectronic devices.