[11a-W321-1~9] 13.9 Compound solar cells

[11a-W321-7] Intermediate-band effect in hot-carrier solar cells

〇Yasuhiko Takeda¹ (1.Toyota Central R&D Labs.)

Keywords:hot-carrier solar cells, intermediate-band solar cells, intraband transition

I have proposed that two-step photo-excitation of carriers is feasible in hot-carrier solar cells (HC-SCs), like that in intermediate-band solar cells (IB-SCs). The second excitation from the IB to the conduction band (CB) in an IB-SC is regarded to make the carriers in the unoccupied band hot. In an analogous way, in an HC-SC, a photo-excited carrier arising from the interband transition can be further excited by the next photon via the intraband transition. In other words, the lower-energy states in the CB function as the IB. Owing to this IB effect, the absorbed energy increases while the energy dissipation associated with the hot-carrier extraction decreases under the optimal conditions. Consequently, the limiting conversion efficiency of the HC-SCs improves by up to 6−9% (absolute) compared to that with no IB effect, under the condition of the carrier thermalization time of 1 ns and 1000-times concentrated solar illumination.