. 2014 Jan 10;16(2):53–65. doi: 10.1021/co3001583

Table 2. Qualitative Relations between Cell Bandgap and the Copper-Oxide Composition.

bandgap range (eV)	CuO	Cu₄O₃	Cu₂O	symbol
1.6–1.68	high	high	low	∗
1.69–2.03	low	high	high	Δ
2.04–2.12		high	high	□
2.13–2.37		low	high	⋈
2.38–2.57			high	×