Provided are photovoltaic devices with polycrystalline type II-VI semiconductor absorber materials including n-type absorber compositions and having p-type hole contact layers are described herein. Methods of treating semiconductor absorber layers and forming hole contact layers are described.

According to one embodiment, a solar cell includes a first electrode, a second electrode, and a photoelectric conversion layer disposed between the first electrode and the second electrode. In a case where a photoluminescence spectrum of the photoelectric conversion layer is measured at a temperature of 100 K or lower, a first maximum value (A) which is a maximum value of emission intensity in a wavelength range of more than 650 nm and 1000 nm or less is 100 times or less of a second maximum value (B) which is a maximum value of emission intensity in a wavelength range of 600 nm or more and 650 nm or less (A100B).

A method of making a non-toxic perovskite/inorganic thin-film tandem solar cell including the steps of depositing a textured oxide buffer layer on an inexpensive substrate, depositing a metal-inorganic film from a eutectic alloy on the buffer layer; and depositing perovskite elements on the metal-inorganic film, thus forming a perovskite layer based on a metal from the metal-inorganic film, incorporating the metal into the perovskite layer.

The disclosure describes multi-junction solar cell structures that include two or more graded interlayers.

An alloy composition for a subcell of a solar cell is provided that has a bandgap of at least 0.9 eV, namely, Ga.sub.1-xIn.sub.xN.sub.yAs.sub.1-y-zSb.sub.z with a low antimony (Sb) content and with enhanced indium (In) content and enhanced nitrogen (N) content, achieving substantial lattice matching to GaAs and Ge substrates and providing both high short circuit currents and high open circuit voltages in GaInNAsSb subcells for multijunction solar cells. The composition ranges for Ga.sub.1-xIn.sub.xN.sub.yAs.sub.1-y-zSb.sub.z are 0.07x0.18, 0.025y0.04 and 0.001z0.03.

The disclosure describes multi-junction solar cell structures that include two or more graded interlayers.

A multijunction solar cell and its method of manufacture including interconnected first and second discrete semiconductor regions disposed adjacent and parallel to each other in a single semiconductor body, including first top subcell, second (and possibly third) lattice matched middle subcells; a graded interlayer adjacent to the last middle solar subcell; and a bottom solar subcell adjacent to said graded interlayer being lattice mismatched with respect to the last middle solar subcell; wherein the interconnected regions form at least a four junction solar cell by a series connection being formed between the bottom solar subcell in the first semiconductor region and the bottom solar subcell in the second semiconductor region.

A multijunction solar cell and its method of manufacture including interconnected first and second discrete semiconductor regions disposed adjacent and parallel to each other in a single semiconductor body, including first top subcell, second (and possibly third) lattice matched middle subcells; and a bottom solar subcell adjacent to said last middle subcell and lattice matched thereto; wherein the interconnected regions form at least a four junction solar cell by a series connection being formed between the bottom solar subcell in the first semiconductor region and the bottom solar subcell in the second semiconductor region.

A multijunction solar cell which includes: an upper first solar subcell having a first band gap; a second solar subcell adjacent to said upper first solar subcell and having a second band gap smaller than said first band gap; a third solar subcell adjacent to said second solar subcell and having a third band gap smaller than said second band gap; a graded interlayer adjacent to said third solar subcell, said graded interlayer having a fourth band gap greater than said third band gap; and a lower fourth solar subcell adjacent to said graded interlayer, said lower fourth solar subcell having a fifth band gap smaller than said third band gap such that said lower fourth solar subcell is lattice mismatched with respect to said third solar subcell.

A method of forming a multijunction solar cell including an upper subcell, a middle subcell, and a lower subcell by providing a substrate for the epitaxial growth of semiconductor material; forming a first solar subcell on the substrate having a first band gap; forming a second solar subcell over the first solar subcell having a second band gap smaller than the first band gap; forming a graded interlayer over the second subcell, the graded interlayer having a third band gap greater than the second band gap; forming a third solar subcell over the graded interlayer having a fourth band gap smaller than the second band gap such that the third subcell is lattice mismatched with respect to the second subcell; and forming a contact composed of a sequence of layers over the first subcell at a temperature of 280 C. or less and having a contact resistance of less than 510.sup.4 ohms-cm.sup.2.