Improved efficiency of Al0.36Ga0.64As solar cells with a pp(-)n(-)n structure

Improvement of efficiency of Al0.36Ga0.64As solar cells is advanced in two aspects of minority-carrier lifetime: reduction of majority-carrier concent ration in the emitter and base layers, and reduction of deep levels in the back-surface-field (BSF) layer. A pp(-)n(-)n structure is proposed to optim ize the use of the effect of reduced majority-carrier concentration, and it s effectiveness verified in a preparatory experiment on Al0.3Ga0.7As solar cells. A very poor photoluminescence (PL) decay time (below 0.3 ns) of a BS F layer heavily doped with Si becomes 14-fold longer when Se is applied to the dopant instead of Si, resulting in an improvement of the external quant um efficiency near the absorption edge. These two aspects of this study lea d to the realization of 16.6% efficiency under 1-sun, AM 1.5 global conditi ons with an Al0.36Ga0.64As solar cell. (C) 2001 Elsevier Science B.V. All r ights reserved.