The environmental toxicity of Pb-based organic-inorganic halide perovskite is one of the most critical factors that hinder the commercialization of perovskite solar cells (PSCs). Reducing the amount of Pb usage by decreasing the thickness of the perovskite absorption layer (the so-called physical lead reduction) is an important approach to relieve the toxicity of Pb-based PSCs. However, reducing the thickness of the absorption layer will weaken the light-harvesting capacity of the solar cell and thus remarkably decrease the power conversion efficiency (PCE) of the devices. In this work, plasmonic Au@Ag@SiO2 nanorods with tunable resonance extinction are prepared and introduced into the mesoporous TiO2 electron transport layer of the PSCs with a much thinner active layer. Considerable improvement in light absorption is observed for the Au@Ag@SiO2 incorporated perovskite films, especially in the long-wavelength zone (550~750 nm), due to the light-trapping effect arising from the local surface plasmon resonance (LSPR) of metal nanorods.The results show that PSCs suffer only a 14.1% reduction in PCE (from 19.1% to 16.4%) with a 63.9% reduction in Pb usage, when the thickness of perovskite film decreased from 720 nm to 260 nm. This study demonstrates that utilizing the LSPR effect of metal plasmonic particles can substantially reduce the lead content of PSCs while maintaining high photoelectric conversion efficiency.

perovskite solar cells; physical lead reduction; plasmonic metal nanorods; local surface plasmon resonance; thin absorption layer