Enhanced external radiative efficiency for 20.8% efficient single-junction GaInP solar cells

Abstract

We demonstrate 1.81 eV GaInP solar cells approaching the Shockley-Queisser limit with 20.8% solar conversion efficiency, 8% external radiative efficiency, and 80–90% internal radiative efficiency at one-sun AM1.5 global conditions. Optically enhanced voltage through photon recycling that improves light extraction was achieved using a back metal reflector. This optical enhancement was realized at one-sun currents when the non-radiative Sah-Noyce-Shockley junction recombination current was reduced by placing the junction at the back of the cell in a higher band gap AlGaInP layer. Electroluminescence and dark current-voltage measurements show the separate effects of optical management and non-radiative dark current reduction.

Experimental demonstration of enhanced photon recycling in angle-restricted GaAs solar cells

“…High ERE cells are already being developed for III-V materials to achieve the highest possible voltage and efficiency, and these cells are ideal candidates for a broader applicability of the angle restriction approach. 10 As further improvements are made in III-V cell technology and other materials reach the high ERE regime, this approach holds promise for signicantly increasing cell efficiencies in a at plate geometry. View Article Online…”

Device characterization for design optimization of 4 junction inverted metamorphic concentrator solar cells

“…Each junction of our 4J solar cell, including the metamorphic junctions, has very respectable IRE quality. Indeed, the GaInP junction is very high since we have used a rear-heterojunction design 10 and, while the GaAs junction could be improved at one-sun, it becomes nearly perfect at high currents.…”

“…The EL light emitted from each junction is quantified 1,10 as the forward injection current density is varied in the dark. The emitted spectra shown in figure 3 were normalized by the spectroradiometer calibration to give units of photon flux / area / wavelength.…”

Optimization of Multijunction Solar Cells Through Indoor Energy Yield Measurements

“…1 shows representative performance maps obtained for similar inverted GalnP/GaAs 2J solar cells with different magnitudes of LC as quantified by the LC factor (7712) [4]. The different LC factors are obtained by using GalnP top cells with different internal luminescence efficiencies as their junction position is changed, as described in [10]. Iso-P max contours are plotted against the equivalent number of suns in each subcell.…”