QUANTUM-WELL SOLAR-CELLS

In this paper we discuss the potential advantages of quantum wells (QW s) for enhancing solar cell efficiency. We present recent experimental results which show that the open-circuit voltage (V-oc) of the quantu m well solar cell (QWSC) is enhanced over that of comparable conventio nal cells formed from the well material, by more than the change in th e absorption edge. We also report on theoretical and experimental stud ies which seek to determine the quasi-Fermi level separation in quantu m wells inside a p-i-n system in order to understand the voltage behav iour of QWSCs and to be able to estimate the efficiency enhancements w hich may be achieved in the radiative limit. We discuss QWSCs in the I nP/InGaAs lattice matched system and present results which show that Q WSCs in this deep well system have a better Variation of efficiency wi th temperature than conventional cells made from either the well or ba rrier material. This is important for applications involving concentra ted sunlight. We also consider the advantages of quantum well cells in the area of thermophotovoltaics (TPV).