Cu2S
chalcocite · cuprous sulfide
Chalcocite is a semiconducting copper sulfide mineral that is highly stable and widely studied for its potential in electronic and energy-related applications.

About chalcocite
Chalcocite is a semiconducting copper sulfide that exists as a near-hull phase, indicating it is a stable and readily synthesizable material. Its electronic properties make it a subject of significant interest for researchers investigating sustainable energy conversion and thin-film technologies. With a high degree of structural diversity reported across various databases, this compound serves as a foundational material in the study of metal chalcogenides. Its ability to maintain structural integrity under various conditions underscores its potential for specialized electronic applications.
Key Properties
Cross-validated computational properties for chalcocite, aggregated across 4 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of Cu2S. Tight agreement means computed properties can be trusted without re-running calculations.
Agreement ScoreA normalized confidence score summarizing how closely independent DFT databases agree. Higher scores mean tighter cross-source agreement.
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
Reported Structures
Lowest-energy structures reported for Cu2S, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| P21/c (No. 14) | monoclinic | 0.35 | 0.0126 | -10.109 | 5.87 |
| P43212 (No. 96) | tetragonal | 0.13 | 0.0195 | -10.102 | 6.06 |
| Imm2 (No. 44) | orthorhombic | 0.16 | 0.0558 | -10.065 | 5.78 |
| C2/c (No. 15) | monoclinic | 0.00 | 0.0569 | -10.064 | 5.44 |
| C2/m (No. 12) | monoclinic | 1.22 | 0.0619 | -10.059 | 3.48 |
| C2/m (No. 12) | monoclinic | 0.92 | 0.0725 | -10.049 | 4.43 |
| Fm-3m (No. 225) | cubic | 0.00 | 0.0943 | -10.027 | 6.17 |
| I41/amd (No. 141) | tetragonal | 0.00 | 0.0955 | -10.026 | 5.66 |
| P1 (No. 1) | triclinic | 0.00 | 0.1109 | -10.010 | 5.30 |
| I-42d (No. 122) | tetragonal | 0.00 | 0.1277 | -9.994 | 6.24 |
| P63/mmc (No. 194) | hexagonal | 0.00 | 0.2385 | -9.883 | 6.30 |
| C2/m (No. 12) | Monoclinic | — | — | — | 3.48 |
Applications
Where chalcocite is used.
Frequently Asked Questions
Common questions about chalcocite, answered from cross-validated data.
What is Cu2S?
Chalcocite is a semiconducting copper sulfide mineral that is highly stable and widely studied for its potential in electronic and energy-related applications.
What is Cu2S used for?
What is the band gap of Cu2S?
Is Cu2S a metal, semiconductor, or insulator?
Is Cu2S thermodynamically stable?
What is the crystal structure of Cu2S?
What is the density of Cu2S?
How many polymorphs of Cu2S are known?
What elements does Cu2S contain?
Where does the data for Cu2S come from?
How It Compares
As a prominent member of the copper-sulfur system, Cu2S serves as a primary reference point for understanding the electronic and structural behavior of binary metal sulfides. It is widely recognized for its semiconducting nature, which distinguishes it from more metallic or insulating counterparts within the broader family of chalcogenide compounds.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- mpaloe — Data from mpaloe.
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
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