Enhanced intraband absorption in two-step photon upconversion solar cells with a double-tunnel-junction structure

Koichiro Matsuzawa, Shigeo Asahi, Takashi Kita

Two-step photon upconversion solar cells (TPU-SCs) belong to the class of solar cells that in principle can exceed the Shockley--Queisser limit for single-junction solar cells. A T…