Subcells Analysis of Thin‐Film Four‐Junction Solar Cells Using Optoelectronic Reciprocity Relation

Abstract

A thin‐film AlGaInP/AlGaAs/InGaAs/InGaAs inverted metamorphic multijunction solar cell with a bandgap of 1.96/1.53/1.16/0.83 eV is fabricated. The photoelectric conversion efficiency reaches 34.89% with an open‐circuit voltage of 3.54 V under AM1.5 G spectrum. The analysis of individual subcells is the key to evaluating the performance of multijunction solar cells. The current density versus voltage characteristics of four subcells are calculated using optoelectronic reciprocity relation between the external quantum efficiency and the different injection current densities electroluminescence. The analysis of the performance characteristics of four subcells concludes that the key to limiting the overall efficiency improvement is the deep‐level recombination of the AlGaInP top subcell and the bulk recombination of 0.83 eV InGaAs bottom subcell. Targeted optimization of the top subcell and the bottom subcell is expected to significantly improve efficiency.

The fabrication of flexible and large‐size inverted metamorphic five‐junction solar cells

“…22,29,37 The external quantum efficiency (EQE) measurements were taken under a self-built system, including ABET LS150W Xenon lamp, PI Acton SP-2335 grating monochromator, SR540 chopper, and SR830 lock-in amplifier. 38 current, and the photocurrent matching optimization of the bottom cell will be carried out in the future to improve the overall performance of the 5J solar cells. In addition, the improvement of high-quality epitaxy at the entire wafer level is also needed.…”

Flexible Encapsulation and Module of Thin‐Film GaInP/GaAs/InGaAs Solar Cells

“…This single source solar simulator does not have the spectral adjustment capabilities required for multi-junction solar cell measurements. The detailed I-V measurement methods can be found in the study by Long et al [26,29] Figure 9a shows the I-V characteristics of the flexible solar cell before and after lamination. Table 2 shows the corresponding photoelectric characteristic parameters.…”

Simple Processing and Analysis of Flexible III–V Multijunction Solar Cells Using Low‐Temperature Transfer Technology

“…W oc,i is the bandgap‐voltage offset of the subcell, and the formula is as followswhere E g,i is the bandgap of the subcell. The external radiative emission efficiency ( η ext,i ) of a subcell can be derived from the Shockley–Queisser (SQ) dark current density ( J 0,rad,i ) and the SQ detailed balance or radiative limit ( V oc,rad,i ), and the detailed information can be found in the study by Long et al [ 20 ] In addition, the forward current density in the dark of a junction is the sum of a diffusion current density ( n = 1) and of recombination current density ( n = 2). [ 35,36 ] Therefore, from the semilogarithmic slope of the J–V curves, the diode quality factor ( n i ) is approximately determined with the relation…”

“…In the conventional IMM solar cell processing technology, the fabrication of the flexible devices typically involves a centimeter-scale wafer bonding by adhesive or Au-Au materials to transfer the epilayers for many times. [13][14][15][16][17] Figure 1a shows a typical feasible technical route, which is our previous usual route, [18][19][20] and this solution requires the transfer of the epilayers twice. First, p-electrode is deposited on the surface of the epilayers and then is bonded to the first temporary handle.…”