Perovskite-Hematite Tandem Cells for Efficient Overall Solar Driven Water Splitting.
Photoelectrochemical water splitting half reactions on semiconducting photoelectrodes have received much attention but efficient overall water splitting driven by a single photoelectrode has remained elusive due to stringent electronic and thermodynamic property requirements. Utilizing a tandem configuration wherein the total photovoltage is generated by complementary optical absorption across different semiconducting electrodes is a possible pathway to unassisted overall light-induced water splitting. Because of the low photovoltages generated by conventional photovoltaic materials (e.g., Si, CIGS), such systems typically consist of triple junction design that increases the complexity due to optoelectrical trade-offs and are also not cost-effective. Here, we show that a single solution processed organic-inorganic halide perovskite (CH3NH3PbI3) solar cell in tandem with a Fe2O3 photoanode can achieve overall unassisted water splitting with a solar-to-hydrogen conversion efficiency of 2.4%. Systematic electro-optical studies were performed to investigate the performance of tandem device. It was found that the overall efficiency was limited by the hematite's photocurrent and onset potential. To understand these limitations, we have estimated the intrinsic solar to chemical conversion efficiency of the doped and undoped Fe2O3 photoanodes. The total photopotential generated by our tandem system (1.87 V) exceeds both the thermodynamic and kinetic requirements (1.6 V), resulting in overall water splitting without the assistance of an electrical bias.
†School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798.
Gurudayal
‡Energy Research Institute @NTU (ERI@N), Research Techno Plaza, X-Frontier Block, Level 5, 50 Nanyang Drive, Singapore 637553.
Dharani
D
Sabba
‡Energy Research Institute @NTU (ERI@N), Research Techno Plaza, X-Frontier Block, Level 5, 50 Nanyang Drive, Singapore 637553.
Mulmudi Hemant
MH
Kumar
†School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798.
Lydia Helena
LH
Wong
†School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798.|§Department of Life Sciences, Imperial College London, London, United Kingdom.
James
J
Barber
∥Laboratory of Photonics and Interfaces, Department of Chemistry and Chemical Engineering, Swiss Federal Institute of Technology, Station 6, CH-1015 Lausanne, Switzerland.
Michael
M
Grätzel
†School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798.|‡Energy Research Institute @NTU (ERI@N), Research Techno Plaza, X-Frontier Block, Level 5, 50 Nanyang Drive, Singapore 637553.
Nripan
N
Mathews
D017610:Calcium Compounds / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D010782:Photolysis; D013472:Sunlight; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D017610:Calcium Compounds; D005290:Ferric Compounds; D010087:Oxides; D014867:Water; C059910:perovskite; C000499:ferric oxide; D014025:Titanium
CH3NH3PbI3; Perovskite solar cells; hematite; photoelectrochemical cell; tandem; unassisted water splitting