Overcoming the luminescent coupling effect in experimental search for the actual quantum efficiency values in multi-junction solar cells

A new experimental procedure to overcome luminescent coupling effect in a multi-junction solar cell is proposed. The procedure was used to obtain the true (hereinafter the actual) external quantum efficiency EQE(λ) values of Ge subcell, and consists of the following steps: 1) photon-coupled characteristic determination; 2) initial EQE(λ) measurement conditions choice and fixation; 3) EQE(λ) measurement with the conventional method; 4) actual EQE(λ) data search with use of photon-coupled characteristic.