The theoretical limit for silicon solar cells is 29.3 percent due to physical material properties. By combining layers of organic molecules into the solar cell, which utilize a quantum mechanical process known as ‘singlet exciton fission’ to split certain energetic light, the electrical current can be doubled in that energy range
Researchers from Helmholtz-Zentrum Berlin (HZB), along with an international collaboration, have devised this novel idea. The effect they used exists in some organic crystals and is known as "singlet exciton fission" (SF). In order for this multiplier effect to be potential, charge carrier pairs have to achieve specific quantum physical conditions i.e. all their spins have to be parallel, charge carrier pairs, called triplet exciton.
By implementing this concept successfully, they have developed a silicon solar cell with a maximum quantum efficiency of 200 percent, which is double the normal limit, with a theoretical efficiency limit of around 40 percent.