Inverted Configuration of Cu(In,Ga)S<sub>2</sub>/In<sub>2</sub>S<sub>3</sub> on 3D-ZnO/ZnSnO<sub>3</sub> Bilayer System for Highly Efficient Photoelectrochemical Water Splitting
Çiğdem Tuç Altaf, Nazire Simay Sahsuvar, Nazrin Abdullayeva, Özlem Coşkun, Alihan Kumtepe, Emine Karagöz, Mehmet Sankır, Nurdan Demirci Sankır
Abstract
Introducing a zinc stannate, ZnSnO3 (ZTO), layer on hydrothermally grown 3D-zinc oxide (ZnO) nanosheet thin films has been proven to have a quenching effect on the photoluminescence emissions, indicating very slow recombination of photoinduced electron–hole pairs in photoelectrochemical water splitting (PEC) reactions. Motivated by this, the ZnO/ZTO bilayer system has been used as the electron transport layer for copper indium gallium sulfide (CIGS)-based photoelectrodes in PEC applications. Furthermore, the poor photoresistivity of CIGS has been improved via indium sulfide (In2S3) deposition. Consequently, the photoelectrode obtained from the inverted configuration, ZnO/ZTO/CIGS/In2S3, has generated a photocurrent density of 6.4 mA cm–2 at 0.4 V (vs Ag/AgCl), exceeding the performance of ZnO NS/CIGS/In2S3 photoelectrodes by three folds. The highest ABPE and IPCE efficiencies have been calculated as 4.2% and 57%, respectively. More importantly, two cost-effective nonvacuum techniques for large-scale thin film fabrications such as chemical bath deposition (CBD) and ultrasonic spray pyrolysis (USP) methods have been adopted to acquire photoelectrodes with inverted configurations providing an advantageous approach for low-cost photoelectrode design for sustainable energy production.