A tandem photoelectrochemical (PEC) water-splitting device for solar hydrogen production consists of two light absorbers with different bandgaps. Silicon photoelectrodes have been widely investigated as the low bandgap bottom cells of tandem devices because of their bandgap (1.12 eV). Herein, we apply a tunnel oxide passivated contact (TOPCon) on the front and back sides of a Si wafer to prepare a TOPCon Si PEC device. Because TOPCon has a SiO2 tunnel oxide layer providing superior surface passivation and working as a diffusion-blocking layer, TOPCon Si photoelectrodes exhibit superior photovoltage and thermal stability. Both photocathode and photoanode are tested over a broad pH range (0-14) and demonstrate high photovoltages of 640-650 mV under 1 sun illumination and excellent thermal stability by enduring a high processing temperature of up to 600 °C for 1 h in air. These advantages of TOPCon Si would provide high efficiency and great design flexibility for monolithic tandem cells. As a preliminary demonstration of the tandem integration, we test two wired tandem PEC devices based on earth-abundant materials, which are a BiVO4 photoanode-TOPCon Si photocathode and halide perovskite photocathode-TOPCon Si photoanode. These devices show STH conversion efficiencies of 0.24 and 3.6%, respectively.
|Journal||Journal of Materials Chemistry A|
|Number of pages||11|
|Publication status||Accepted/In press - 2023|
Bibliographical noteFunding Information:
This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (No. 2021M3I3A1085009, No. 2022R1I1A1A01063534). This research was supported by the Nano Material Technology Development Program (Green Nano Technology Development Program) through the NRF funded by the Ministry of Education, Science and Technology (No. 2018M3A7B4065662).
© 2023 The Royal Society of Chemistry.