Large-area all-perovskite-based coplanar photoelectrodes for scaled-up solar hydrogen production

Abstract

Recently, lead halide perovskites (LHPs) have been intensively investigated for use as photoelectrodes in photoelectrochemical (PEC) water splitting systems, and PEC water splitting systems with LHP electrodes have shown outstanding solar-to-hydrogen (STH) efficiencies. Despite the significant role of large-scale deployment for practical commercialization, the fabrication of large-area LHP photoelectrodes is rarely investigated in the field of PEC water splitting. Herein, we present a strategy involving immersing an as-coated LHP film in an antisolvent containing cyclohexylammonium iodide (CHAI) for the fabrication of high-quality large-size LHP films for use in unbiased PEC water splitting. CHAI molecules accelerate nucleation kinetics by participating in the formation of an intermediate phase, resulting in uniform high-crystallinity LHP films. Furthermore, CHAI molecules effectively passivate grain boundaries, thereby increasing the photocurrent density and onset potential of PEC devices. Consequently, parallelly illuminated coplanar LHP-based photoelectrodes with dimensions of 8 cm × 8 cm could be stably operated without any applied bias, and they exhibited a record-high STH efficiency of 9.89% and a T₈₀ (the time at which the photocurrent density drops to 80% of its initial value) of 24 h. The hydrogen production rate of our device was 145.56 μmol h⁻¹ cm⁻², which is highly comparable with previously reported values of state-of-the-art unassisted PEC devices.