You searched for: “multiple junction cell
vertical multijunction (VMJ) cell; multiple junction cell
A compound cell made of different semiconductor materials in layers, one above the other.

Sunlight entering the top passes through successive cell barriers, each of which converts a separate portion of the spectrum into electricity, thus achieving greater total conversion efficiency of the incident light.

This entry is located in the following unit: Photovoltaic Conversion Efficiency Terms + (page 23)