Enhanced Efficiency of Metamorphic Triple Junction Solar Cells for Space Applications

Sun

et al. 2021

Solar RRL

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.

Section: Experiments and Resultsmentioning

confidence: 63%

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

Sun

et al. 2021

Solar RRL

“…The high efficiency, high reliability, and long life of the III – V compounds multijunction solar cells have been verified in space power systems. [ 1–4 ] Due to their ultrathin epilayers, III – V solar cells prepared by transfer technology have great advantages in flexible applications for real‐time energy supply systems, such as near‐space airships, drones, new energy vehicles, and smart wearable devices. Inverted metamorphic multijunction (IMM) technology can prevent the degradation of the top cell by finally growing a lattice mismatch cell, which is considered as the most effective solution for flexible multijunction solar cells.…”

Section: Introductionmentioning

confidence: 99%

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

Sun

et al. 2021

Solar RRL

A simple method is proposed for manufacturing the flexible III–V inverted metamorphic solar cells by low‐temperature transfer technology. Benefiting from the special low‐temperature adhesive and the Cu‐plated thin films, only one‐time bonding and extremely easy debonding are needed through the whole process and a negligible effect of residual stress can be obtained, which is critical to large‐size device fabrication. The optical model of light trapping and photon recycling based on the native textured back‐surface reflector of the flexible solar cell is constructed to design the antireflection coating. The flexible 4 in solar cells with a weight‐area density of only 169 g m−2 are successfully mass‐produced. The analysis of the individual subcells using optoelectronic reciprocity relation indicates that the GaAs middle subcell should be further optimized to improve the performance. The technique can be expected to achieve mass production of flexible high‐efficiency large‐size solar cells with low cost.

“…III–V compound semiconductor materials cover the entire solar spectral absorption gap, which are extremely suitable for multijunction tandem solar cells. When solar cells exceed three‐junction materials, there is a lattice mismatch among the subcells 5–7 . The multijunction solar cells, such as GaInP/GaAs/InGaAsP/InGaAs, 8,9 are prepared by the wafer bonding method to avoid lattice mismatch stress.…”

Section: Introductionmentioning

confidence: 99%

“…When solar cells exceed three-junction materials, there is a lattice mismatch among the subcells. [5][6][7] The multijunction solar cells, such as GaInP/GaAs/InGaAsP/InGaAs, 8,9 are prepared by the wafer bonding method to avoid lattice mismatch stress. However, bonding equipment is required, and it is difficult to ensure large size uniformity.…”

Section: Introductionmentioning

confidence: 99%

Failure analysis of thin‐film four‐junction inverted metamorphic solar cells

Progress in Photovoltaics

Huang

et al. 2020

Inverted metamorphic solar cells play an important role in the field of photovoltaics, because it can directly grow stacked tandem junctions with different bandgaps according to the spectrum. We have found that the four‐junction AlGaInP/AlGaAs/InGaAs/InGaAs solar cells with the bandgap of 1.96/1.55/1.17/0.83 eV on the basis of the inverted metamorphic three‐junction AlGaInP/AlGaAs/InGaAs materials will cause a serious decrease in short‐circuit current density but with a normal open‐circuit voltage. The sharp decrease in short‐circuit current density is not attributed to the mismatched buffers dislocations penetrating into the active region of the InGaAs subcells but resulted from the minority carrier recombination due to defects in the AlGaInP subcell, which is observed directly from transmission electron microscopy, external quantum efficiency, electroluminescence, and secondary ion mass spectrometry measurements. The process of growing AlGaInP materials by metal–organic chemical vapor deposition easily introduces Al‐O deep‐level defects, resulting in the poor collection of minority carriers in AlGaInP materials. After improving the growth conditions of AlGaInP materials, a four‐junction solar cell with a photoelectric conversion efficiency of 34.9% and an open‐circuit voltage of 3.53 V was obtained.