A method of forming a multijunction solar cell that includes an InGaAs buffer layer and an InGaAlAs grading interlayer disposed below, and adjacent to, the InGaAs buffer layer. The grading interlayer achieves a transition in lattice constant from one solar subcell to another adjacent solar subcell.

A multijunction solar cells that include one or more graded-index structures disposed directly above the growth substrate beneath a base layer of a solar subcells. In some embodiments, the graded-index reflector structure is constructed such that (i) at least a portion of light of a first spectral wavelength range that enters and passes through a solar cell above the graded-index reflector structure is reflected back into the solar subcell by the graded-index reflector structure; and (ii) at least a portion of light of a second spectral wavelength range that enters and passes through the solar cell above the graded-index reflector structure is transmitted through the graded-index reflector structure to layers disposed beneath the graded-index reflector structure. The second spectral wavelength range is composed of greater wavelengths than the wavelengths of the first spectral wavelength range.

A space vehicle comprising: a housing having a first side and an opposite side, and an axis; a first elongated, rectangular sheet including an array of transducer devices including multijunction solar cells mounted on, and extending from a surface of the first side of the housing, and a second elongated, rectangular sheet including an array of transducer devices including multijunction solar cells mounted on and extending from a surface of the second side of the housing that extend radially from the housing and orthogonal to the axis of the housing in a direction opposite to that of the first flexible elongated rectangular sheet, wherein the selection of the composition of the subcells and their band gap of the multijunction solar cells maximizes the efficiency of the solar cell at the end-of-life EOL in the application of one of (i) a low earth orbit (LEO) satellite that typically experiences radiation equivalent to 5×10.sup.14 electron fluence per square centimeter (“e/cm.sup.2”) over a five year EOL, or (ii) a geosynchronous earth orbit (GEO) satellite that typically experiences radiation in the range of 5×10.sup.14 e/cm.sup.2 to 1×10.sup.15 e/cm.sup.2 over a fifteen year EOL, with the efficiency of the multijunction solar cells being less at the BOL than the EOL.

A method of fabricating a multijunction solar cell panel by providing a plurality of multijunction solar cells;

dispensing out uncured silicone coating on the solar cells using an automated process with visual recognition, and curing the silicone coating on the solar cell to complete the Cell-Interconnect-Cover Glass (CIC) assembly.

A multijunction solar cell assembly and its method of manufacture including interconnected first and second discreate semiconductor body subassemblies disposed adjacent and parallel to each other, in the sense of the incoming illumination, each semiconductor body subassembly including first top subcell, and possibly third middle subcells and a bottom solar subcell; wherein the interconnected subassemblies form at least a Three junction solar cell by a series connection being formed between the bottom solar subcell in the first semiconductor body with its at least least two junctions and the bottom solar subcell in the second semiconductor body representing the additional junction.

A method of manufacturing an inverted metamorphic multijunction solar cell by providing a growth semiconductor substrate with a top surface having a doping in the range of 110.sup.18 to 110.sup.20 charge carriers/cm.sup.3; depositing a window layer for a top (light facing) subcell subsequently to be formed directly on the top surface of the growth substrate; depositing a sequence of layers of semiconductor material forming a solar cell directly on the window layer; providing a surrogate substrate on the top surface of the sequence of layers of semiconductor material, and removing a portion of the semiconductor substrate so that only the high doped surface portion of the substrate, having a thickness in the range of 0.5 m to 10 m, remains.

The present invention utilizes epitaxial lift-off in which a sacrificial layer is included in the epitaxial growth between the substrate and a thin film III-V compound solar cell. To provide support for the thin film III-V compound solar cell in absence of the substrate, a backing layer is applied to a surface of the thin film III-V compound solar cell before it is separated from the substrate. To separate the thin film III-V compound solar cell from the substrate, the sacrificial layer is removed as part of the epitaxial lift-off. Once the substrate is separated from the thin film III-V compound solar cell, the substrate may then be reused in the formation of another thin film III-V compound solar cell.

A method of is provided as a process of substrate lift-off. The present invention is mainly used for a group III-V solar cell, which has the highest power generation efficiency. An original sacrificial layer is changed into an AlAs oxide layer, which is transformed into an AlO.sub.x sacrificial layer after wet oxidation. The sacrificial layer is then soaked in an oxide-relief solution for etching. Thus, the lift-off process of a GaAs substrate can be harmlessly processed to the complex group III-V solar cell. The GaAs substrate can be recycled to be effectively further reused in photovoltaic devices with reduced cost.

A five junction solar cell and its method of manufacture including an upper first solar subcell composed of a semiconductor material having a first band gap; a second solar subcell adjacent to said first solar subcell and composed of a semiconductor material having a second band gap smaller than the first band gap and being lattice matched with the upper first solar subcell; a third solar subcell adjacent to said second solar subcell and composed of a semiconductor material having a third band gap smaller than the second band gap and being lattice matched with the second solar subcell; a fourth solar subcell adjacent to said second solar subcell and composed of a semiconductor material having a fourth band gap smaller than the third band gap and being lattice matched with respect to the third solar subcell; a graded interlayer adjacent to the fourth solar subcell and having a fifth band gap greater than the fourth band gap; and a bottom solar subcell adjacent to the graded interlayer and being lattice mismatched from the fourth solar subcell and having a sixth band gap smaller than the fifth band gap.

An inverted metamorphic multijunction solar cell comprising: an upper first solar subcell having a first band gap; a middle second solar subcell disposed adjacent to the upper first solar subcell and having a second band gap smaller than said first band gap; a graded interlayer disposed adjacent to the middle second solar subcell and having a band gap that remains constant throughout its thickness; a lower third solar subcell disposed adjacent to said graded interlayer and having a fourth band gap that is smaller than said second band gap such that said third solar subcell is lattice mismatched with respect to said second solar subcell; a back surface field (BSF) layer disposed directly adjacent to the base layer of said lower third solar subcell; at least one distributed Bragg reflector (DBR) layer disposed directly adjacent to the back surface field (BSF) layer.