Hybrid Perovskite‐Based Wireless Integrated Device Exceeding a Solar to Hydrogen Conversion Efficiency of 11%

Abstract A wireless solar water splitting device provides a means to achieve an inexpensive and highly distributed solar‐to‐fuel system owing to its portability, flexible scale, and simple design. Here, a highly efficient hydrogen‐generating artificial leaf is introduced, which is a wireless configuration for converting solar energy into chemical energy, by integrating a hybrid perovskite (PSK) as the light absorber with catalysts for electrochemical reaction. First, a single integrated photoelectrochemical photocathode, and a spatially decoupled hydrogen evolution reaction catalyst, are fabricated. A decoupled geometry is adopted to enable the physical protection of the PSK layer from the electrolyte, thus allowing excellent stability for over 85 h. Additionally, an efficient dual photovoltaic module photocathode is fabricated to produce sufficient photovoltage to drive water splitting reactions, as well as a high photocurrent to achieve the applied‐bias photoconversion efficiency (13.5%). To investigate the overall water splitting performance, a NiFe–OH catalyst is employed, and the device with a wired configuration achieves a photocurrent density of 9.35 mA cm −2 , corresponding to a solar to hydrogen (STH) efficiency of 11.5%. The device with a fully integrated wireless artificial leaf configuration exhibited a similar STH efficiency of over 11%, demonstrating the effectiveness of this cell design.