CuGaSe2/ c-Si tandem solar cell exceeding 1.1 Volt Voc with ITO or tunnel junction at the interface

We report on the developments related to the elaboration of 2-terminals CuGaSe
₂
(CGSe) on crystalline silicon (c-Si) monolithic tandem solar cells. Two different approaches for the interface layers between both cells were investigated. The first one uses thin ITO films as recombination layers. The second is based on a passivating tunnel junction formed by a p-type poly-crystalline Si films deposited on the implanted n
⁺
emitter of the silicon subcell, both highly doped layers being separated by an ultra-thin interfacial silicon oxide films. The first functional CuGaSe
₂
/c-Si tandem devices were recently elaborated, with for both approaches, Open Circuit Voltage (Voc) values exceeding 1.1V.