High efficiency Cu₂O tandem solar cell system that contributes to carbon neutrality

Toshiba Corporation Corporate Research & Development Center
Toshiba Energy Systems & Solutions Corporation

A transparent PV cell using cuprous oxide (Cu₂O) is tandem with silicon (Si) solar cell, which are currently widely used, that achieves the world's top level of power generation efficiency, so the solar cell is expected to be mounted on electric mobility including electric vehicles and to be applied to independent power systems and distributed power supplies.
With this transparent Cu₂O solar cell (small cell) alone, the power generation efficiency was improved by 1.0 points from 9.5% announced September 2022^*1, achieving the world's highest^*2 power generation efficiency of 10.5%^*3. In addition, the power generation efficiency of the entire Cu₂O solar cell layered on a high efficiency Si solar cell with a power generation efficiency of 25.6% can be estimated to reach 30%, confirming that it has the potential to exceed the efficiency of the world's current most efficient Si solar cell at 27.1%^*4.
Toshiba Corporation Corporate Research & Development Center and Toshiba Energy Systems & Solutions Corporation estimated that if this Cu₂O/Si tandem solar cell was mounted on an electric vehicle (EV), its cruising range would be approximately 39 km per day without charging^*5. Going forward, the two companies will aim to achieve an EV that can be driven for long hours without charging and contribute to the electrification of transportation (or achievement of a carbon neutral society) by mounting the cell onto trains or other mobility.
Part of this achievement was obtained from the results of a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO).

• A new record was set for the highest power generation efficiency in the world for a transparent Cu₂O solar cell for the achievement of a high-efficiency, low-cost, high reliability tandem solar cell.
• Survey by Toshiba Corporation, as of December 2023. 
• TOSHIBA REVIEW, Vol. 79, No. 2, March 2024, page 9, "High-efficiency Tandem Solar Cells Made by Stacking Si Cells with Cu₂O Cells, with Power Generation Efficiency Exceeding 10%" (PDF)(2.14MB) (Japanese only)
  Shibasaki, et al., The 71st JSAP Spring Meeting 2024, "Improving the Power Generation Efficiency of Cu₂O Top Cells to Achieve Highly Efficient, Reliable Cu₂O/Si Tandem Solar Cells"
• World’s highest efficiency for Si solar cells as of July 2024. NREL  "Best Research-Cell Efficiency Chart" https://www.nrel.gov/pv/cell-efficiency.html

• An estimation with reference to "PV-Powered Vehicle Strategy Committee Interim Report" of the New Energy and Industrial Technology Development Organization (NEDO). (https://www.nedo.go.jp/news/press/AA5_101114.html (Japanese only))