LIMITING EFFICIENCY OF AN EDGE-ILLUMINATED MULTIGAP SOLAR-CELL

An edge-illuminated multigap photovoltaic system should show an efficiency greater than that obtainable with only a single gap. The theoretical upper limit to the efficiency will occur as the number of different gaps goes to infinity. For this case a detailed balance limit analysis shows that at one sun the predicted efficiency is 64% increasing with intensity to 81% at ten thousand suns. The effects of stimulated emission are included in the calculations but are found to be negligible. Because the expression for the limiting efficiency does not contain any property of a particular semiconductor, it seems to be thermodynamic in character.