CuO

Basic Information

Alternate names:

• copper (ii) oxide
• cupric oxide
• black copper
• Tenorite – named after Professor Michele Tenore, an Italian botanist at the University of Naples, Italy [1]

CuO is a secondary copper mineral, a rare earth metal, and the most stable form of oxidized copper

Found in the oxidized zone of hydrothermal copper deposits, a volcanic sublimate [1]

CuO is a p-type semiconductor

Crystal Structure

X-ray Diffraction data [2]:

X-RAY WAVELENGTH:     1.541838

      MAX. ABS. INTENSITY / VOLUME**2:      94.00384821   

2θ	Intensity	D-Spacing	H	K	L	Multiplicity
32.72	5.84	2.7372	1	1	0	4
35.64	30.43	2.5191	0	0	2	2
35.76	80.26	2.5108	-1	1	1	4
38.96	100	2.3118	1	1	1	4
39.26	23.3	2.2947	2	0	0	2
46.54	1.59	1.9516	-1	1	2	4
49.1	28.24	1.8553	-2	0	2	2
51.67	1.03	1.769	1	1	2	4
53.76	11.47	1.705	0	2	0	2
58.72	14.81	1.5724	2	0	2	2
61.92	20.59	1.4986	-1	1	3	4
66.18	16.04	1.412	0	2	2	4
66.8	15.56	1.4004	-3	1	1	4
68.34	9.91	1.3726	1	1	3	4
68.57	14.08	1.3686	2	2	0	4
73.01	7.87	1.296	3	1	1	4
75.48	5.82	1.2596	0	0	4	2
75.77	6.97	1.2554	-2	2	2	4
80.76	2.32	1.1899	-2	0	4	2
83.06	5.17	1.1628	-3	1	3	4
83.66	5.08	1.1559	2	2	2	4
84.43	4	1.1474	4	0	0	2

 

A graph of XRD patterns of copper oxide thin films as deposited and annealed at various temperatures can be found from reference [3].

A graph of  X-ray powder diffraction pattern of CuO nanoparticles (sample no. 2) (a) before calcination, (b) after calcination (PEG template), (c) after calcination (PVA template) and (d) after calcination (PPG template) can be found from reference [1].

PV Applications

CuO has been used in solar cell research. At the University of Shiga, CuO layers were spin-coated at 100 nm thick on FTO substrate. It was concluded that the formation of higher quality CuO thin films may improve future CuO cell efficiency.

A diagram of the structure of a FTO/CuO//Al heterojunction solar cell can be found from reference [2].

The solar cell of structure CuO(300°C)/ (spin.) gave a power conversion efficiency (ɳ) of 1.5E-4%, a fill factor (FF) of 0.25, short circuit current density (JSC) of 13 μAcm^-2 and open-circuit voltage (V_OC) of 45mV. The solar cell CuO(450°C)/ (eva.) showed a similar photovoltaic performance. This table can be found from reference [2].

At Chiang Mai University, ZnO dye-sensitized solar cells (DSSCs) with different photoelectrodes were studied on the effect of CuO layer as a barrier layer toward power conversion characteristics.

Schematic diagram of DSSC structures with different photoelectrodes for ZnO/CuO layer can be found from reference [3].

Semiconductor oxides are a promising alternative to silicon-based solar cells because they possess high optical absorption and are composed of low cost materials. [4]

Potential applications: photoconductive, photothermal, catalysis and gas sensor 

CuO has been employed in photo-electrochemical cells

CuO has been used as a hole transfer layer and barrier layer for dye-sensitized solar cells [3], active layer in various types of solar cells [5], passive layer in solar-selective surfaces.

It would make a good selective absorbing layer because of its high solar absorbance and low thermal emittance.

Prepared by: spraying, chemical conversion, chemical brightening, etching, electrodeposition, electronbeam evaporation, reactive DC sputtering and chemical vapor deposition

		25°C	100°C	200°C	300°C
	αs	0.73	0.73	0.73	0.73
CuO	ε	0.040	0.038	0.044	0.052
300°C	αs/ε	18.2	19.1	16.4	13.9
	αs	0.90	0.90	0.90	0.90
CuO	ε	0.52	0.55	0.59	0.65
500°C	αs/ε	1.73	1.63	1.51	1.39

[10] Solar absorptance α_s, thermal emittance ε, and selectivity α_s/ε of CuO films deposited on gold-coated glass substrate

CuO film prepared at 500°C shows smaller values of selectivity, indicating that the well-crystallized CuO film is not useful as a solar selective surface.

Basic Parameters at 300 K

Crystal Structure	Monoclinic	[11]
Group of Symmetry	– C 2/c	[11], [12]
Unit Cell Volume:	V 80.63 ų
Density	6.31 g/cm³
Dielectric constant	18.1	[13]
Effective electron mass	0.4-0.95	[14]
Effective hole masses	7.9 mo	[14]
Electron affinity	4.07 eV
Lattice constants	a= 4.652 Å b= 3.410Å c= 5.108 Å	[11], [12]
Energy band-gap	1.35 eV	[15]

Band Structure and Carrier Concentration

A diagram showing the Band gap: 1.3 – 1.7 eV with a black color and a partial transparency in the visible range can be found from reference [16].

Temperature Dependences:

A graph of the temperature dependence of conductivity plotted as ln(s) vs. 10^3/T in a temperature range 125–365 K and a graph of the temperature dependence of conductivity plotted as ln(σT^1/2) vs. 10³/T can be found from reference [17].

Effective Mass [17]: 7.9 m₀  

Electrical Properties

Limited data available

CuO is antiferromagnetic

                                       

                     

Mobility holes [18]:	0.1 cm2 V−1s−1
Electric dipole moment [19]:	4.500 .5 (Debye)

A graph of the device current density voltage (J-V) curves both in the dark and light (under AM 1.5 100 mW cm−2 illumination) of a bi-layer cell with a ~40 nm thick CuO layer can be found from reference [6].

A graph of the measured J-V characteristics of CuO/  thin films in the dark and under AM1.5 illumination can be found from reference [2].

Optical Properties

Basic Information [20]:

Type:	Anisotropic
Anisotropism:	Strong, blue to grey
Bireflectance:	Strong
Color in reflected light:	light gray with golden tint
Pleochromism:	Weak
Comments:	Dictinct, light to dark brown
Absorption coefficient [21]:	α=0

A graph of the optical transmittance (T%) spectra of a copper oxide thin film as-deposited and annealed at various temperatures can be found on reference [3].

Refractive Index: n=2.65498 and the Extinction coefficient: k=0 can be found from reference [21].

Thermal Properties

Enthalpy of formation (298.15 K) [19]:	306.27 kJ/mol (Uncertainty: 41.8 kJ/mol)
Entropy (298.15 K) [19]:	234.62 J/mol*K
Integrated heat capacity (0-298.15 K) [19]:	-9.75 kJ/mol
Heat capacity (298.15 K) [19]:	35.69 J/mol*K

A graph of the glancing angle XRD patterns of copper oxide thin film on n-Si wafer at various deposition temperatures, a graph of Cu 2p X-ray photoemission spectra of copper oxide film at various deposition temperatures, and a graph of Spectrophotometric transmittance for copper oxide film deposited at various temperatures can be found from reference [4].

Mechanical Properties

Vibrational zero-point energy [19]:	320.1
Rotational Constants [19]:	A: 0 B: .44454 C: .44454
Product of moments of inertia [19]:	37.92152 amu Å 6.29711E-39 gm cm²
Young’s modulus [23]:	81.6 GPa

References

The development of these pages on photovoltaic materials’ properties was carried out at the University of Utah primarily by undergraduate students Jeff Provost and Carina Hahn working with Prof. Mike Scarpulla. Caitlin Arndt, Christian Robert, Katie Furse, Jash Sayani, and Liz Lund also contributed. The work was fully supported by the US National Science Foundation under the Materials World Network program award 1008302. These pages are a work in progress and we solicit input from knowledgeable parties around the world for more accurate or additional information. Contact earthabundantpv@eng.utah.edu with such suggestions. Neither the University of Utah nor the NSF guarantee the accuracy of these values.

• 1. R. Ranjbar-Karimi, Bazmandegan-Shamili, A., Aslani, A., and Kaviani, K., “Sonochemical synthesis, characterization and thermal and optical analysis of CuO nanoparticles”, Physica B: Condensed Matter, vol. 405, no. 15, pp. 3096 - 3100, 2010.
• 2. a. b. c. R. MOTOYOSHI et al., “Structure and photovoltaic activity of cupric oxide-based thin film solar cells”, Journal of the Ceramic Society of Japan, vol. 118, no. 1383, pp. 1021 - 1023, 2010.
• 3. a. b. P. Raksa, Nilphai, S., Gardchareon, A., and Choopun, S., “Copper oxide thin film and nanowire as a barrier in ZnO dye-sensitized solar cells”, Thin Solid Films, vol. 517, no. 17, pp. 4741 - 4744, 2009.
• 4. a. b. K. Hyun Yoon, Choi, W. Jin, and Kang, D. Heon, “Photoelectrochemical properties of copper oxide thin films coated on an n-Si substrate”, Thin Solid Films, vol. 372, pp. 250 - 256, 2000.
• 5. E. P. S. Tan et al., “Crystallinity and surface effects on Young’s modulus of CuO nanowires”, Applied Physics Letters, vol. 90, no. 16, p. 163112, 2007.
• 6. Y. - F. Lim, Choi, J. J., and Hanrath, T., “Facile Synthesis of Colloidal CuO Nanocrystals for Light-Harvesting Applications”, Journal of Nanomaterials, vol. 20123312825910287, no. 710315291, pp. 1 - 6, 2012.