A promising ternary sulfide bidirectional p–n heterojunction for unassisted tandem photoelectrochemical cells

Abstract

There has been great demand for high-efficiency, low-cost, and abundant photoelectrode materials for photoelectrochemical (PEC) systems. Here, we studied the PEC performance of ternary sulfide photoelectrodes (ZnIn₂S₄ and CuInS₂) with the same nanostructure and applied bidirectional p–n heterojunctions with energy levels that were well matched to the unassisted tandem PEC cell device. Moreover, ZnIn₂S₄/CuInS₂ and CuInS₂/ZnIn₂S₄ were used as a photoanode and photocathode, respectively, in the unassisted tandem PEC cell device, which achieved a relatively high photocurrent density of 0.06 mA cm⁻². This work provides new ideas for the design and manufacture of high-efficiency unassisted tandem PEC cell devices.