Two-Terminal Monolithic In_0.5Ga_0.5P/GaAs Tandem Solar Cells with a High Conversion Efficiency of Over 30%

Abstract

A world-record efficiency of 30.28% has been attained for two-terminal monolithic In0.5Ga0.5P/GaAs tandem solar cells under one-sun air-mass 1.5 global illumination. The cell area has a practical size of 4 cm2. At first, high efficiency In0.5Ga0.5P single junction cells had been developed by improving the minority carrier lifetime. Second, the GaAs single junction cells had been investigated to obtain higher open-circuit voltage. Third, the tandem cell performance had been improved by using an InGaP tunnel junction with AlInP barriers which constitute a double-hetero structure and increase the peak current of the tunnel junction. In addition, the AlInP barrier located beneath the InGaP top cell have been found to be effective for reflecting minority carriers in the top cell and for suppressing the diffusion of zinc from the highly doped tunnel junction toward the top cell during epitaxial growth.

Flexible Thin-Film Tandem Solar Cells With >30% Efficiency

“…3. Device opencircuit voltage (V oc ) in particular was significantly higher than previously published values for an InGaP/GaAs solar cell [9]. Fig.…”

III‐V Solar Cells

“…During MOVPE growth, ordering of InGaP can be controlled by substrate orientation [96] or the use of antimony, that acts as a surfactant and stabilises the growth surface [97,98]. The successful control of ordering has been key to the improvements made to the InGaP/GaAs doublejunction solar cell, resulting in a 30.3% efficiency under 1-sun AM1.5G [99] in 1997. Under most illumination conditions, this solar cell could be improved by either raising the top-cell bandgap or lowering the bottom-cell bandgap.…”

Super-High-Efficiency Iii–v Tandem and Multijunction Cells

“…Both the opencircuit voltage and the short-circuit current of the cells are improved by such wide-gap tunnel junctions without suffering absorption and recombination losses (Takamoto et al, 1997b). It is difficult to obtain a high tunnelling peak current with wide-gap tunnel junctions, so thinning the depletion layer width by formation of a highly doped junction is necessary.…”