III–V triple junctions and MQW-fine tuning at 1 EV in synergy for high efficiency solar cells

High efficiency triple junctions (>40%) in synergy with tuned MQW pin structures may lead to even higher efficiency values for a new class of solar cells that include quantum size effects. This paper exploits the possibility of quantum wells in superlattice form where photocarrier conduction is feasible via thermionic and/or tunneling conduction. Such structures may be designed to absorb at selective bands of the solar spectrum (e.g. 1 eV range); carrier confinement occurs at concentrations from 10¹² - 10¹³ cm² pew quantum well. A top three junction cell is simulated at 28.4% efficiency (AlGaAs/GaAs/GaAs), and bottom multijunction cell (MQW GaAs-Ge superlattice) at 22%. The synergy of the two units leads to a projected efficiency near 44.2%, a clear step to highest efficiencies feasible in the immediate future. Our design opens the way to highly effective solar cells via (a) triple junctions and (b) 2-dimensional electronic transport (c) flexibility in material selection.