Design guides for artificial photosynthetic devices consisting of voltage-matched perovskite/silicon tandem solar-cell modules and electrochemical reactor modules

Abstract

We clarified the design guides for H2- and CO-producing artificial photosynthetic devices. The combination of a voltage-matched (VM) tandem solar-cell (SC) module and an electrochemical (EC) module was adopted. The parallel-connected top and bottom SC modules, in which multiple organic-inorganic hybrid perovskite (PVK) SCs with a bandgap of 1.7 eV and crystalline-silicon SCs were connected in series, respectively, powered the EC module consisting of series-connected multiple EC reactors. It was found that the design parameters of the series-connection numbers must be optimized under the slightly larger solar intensity and higher temperature than the average values, respectively, for minimizing the mismatch between the device operating voltage and SC maximal-power voltage. This is contrasting to that the annual electricity production of the VM SC module coupled with a power conditioner is not sensitive to the optimization condition. Increases in the bandgaps of the PVK SCs do not affect the annual production significantly.

Scalable all‐perovskite double‐ and triple‐junction solar modules: Modeling for configuration optimization

“…36 Then, PVK/c-Si VM modules have been investigated. [37][38][39] However, application of the VM configuration to the monolithically seriesinterconnected modules raises a particular concern; the ohmic loss and optical loss in the transparent electrodes are larger than those for 2J-4T, as follows. The series-connection number of the cells in the top module is smaller than that in the bottom module because the top cells have a larger bandgap and hence a larger maximal-power voltage.…”

“…The objective of the present study is to design the best suited configurations of the 2J and 3J solar modules installed outdoors. For this purpose, we optimized the structures of the modules illustrated in (P sun = 100 mW/cm 2 ) and T cell = 25 C. 60 However, it is not suitable for the structure optimization of solar modules used outdoors, 39,61 because P sun is weaker and T cell is higher mostly in practice. Therefore, instead of using the standard condition, we determined the "average condition."…”

“…In addition, it was found that 2J-4T and -VM are tolerant to large variations in the optimization and operation conditions, as discussed in detail in section S4 in the Supporting Information. 39 On the other hand, 2J-2T involves a practical problem. The PVK at E g,top = 1.86 eV is composed of mixed anions of I and Br, and suffers from low durability caused by segregation to the I-rich phase and Br-rich phase during the operation.…”

“…This is a problem unique to the all-PVK 2T cells and modules, because E g,top of around 1.7 eV is the optimal for the PVK/c-Si and PVK/CIGS. 13,14,16,17,38,39 Comparing 2J-4T and -VM that yield almost the same η annual , the dual output of different voltages of 2J-4T is practically a serious drawback. Thus, it is concluded that 2J-VM would be the most promising candidate for the 2J configuration that provides high η annual with a single output (two terminals), high tolerance to large variations in the optimization and operation conditions, and potentially high durability.…”

Integrated Operation of Artificial-Photosynthetic Reaction and Product Isolation to Output Only Pure Formic Acid

“…We previously constructed a practically large-sized device to synthesize formic acid using solar energy, which was a major milestone toward widespread use of artificial photosynthesis. , The device consisted of 1 m 2 -sized Ru-complex-based cathode electrodes, IrO x -based anode electrodes, and single-crystalline silicon solar cells, achieving a high solar-to-chemical energy conversion efficiency of 10.5%. Then, we tackled remaining challenges: improvements in both activity and durability of the cathode and anode catalysts, , direct reduction of CO 2 in a flue gas eliminating the CO 2 capture and condensation processes, and specific design of solar cells suitable for direct connection to the electrochemical reactors. − In particular, long-term durability is of great importance for practical use. We improved the durability of the Ru-complex-based cathode electrodes to achieve stable operation of the formic-acid synthesis over 3000 h…”