Cadmium telluride (CdTe) CdTe

CdTe · CAS 1306-25-8 · zinc blende, F43m

Cadmium telluride (CdTe) is a zinc-blende compound of cadmium and tellurium with a direct band gap of 1.5 eV at 300 K, per Wikipedia.

8 sources · Updated 2026-11-01 · CC BY 4.0

Evidence level

2 of 5

Lab-measured

Band gap

1.5 eV

Cell efficiency

22.1%

Module efficiency

Up to 19.3%

Ageing

0.3% per year

High-temperature output

5 to 9% more energy

Recipe, share of the weight

  • Cd not statedCadmium
  • Te not statedTellurium

Best for

Utility-scale thin-film PV built on a high-volume line, where Wikipedia records a direct manufacturing cost of $0.57 per watt in 2013

Weakest at

Cadmium toxicity and tellurium supply: Wikipedia prints GHS codes H302, H312, H332, H410 and H411 for CdTe, and the USGS lists tellurium as a critical mineral that is recovered mainly from copper refining

Risk at a glance

  • People No data. No hazard data recorded
  • If it fails Moderate. Cadmium release at high temperature
  • Corrosion Low. First Solar warrants 0.3% per year degradation and a 30-year linear performance warranty.

Quick facts: CdTe

Key properties of CdTe
PropertyValueBasis
Density5.85 g·cm−31 sourced value
Young's modulus52 GPa1 sourced value
Thermal conductivity6.2 W·m/m2·K1 sourced value
Thermal expansion (CTE)0.0000059 /K1 sourced value
Melting point1,041 °C1 sourced value
Specific heat210 J/(kg·K)1 sourced value

What is the density of Cadmium telluride (CdTe)?

Cadmium telluride (CdTe) has a density of 5.85 g·cm−3. The source and test conditions are listed in the properties table on this page.

What is the thermal conductivity of Cadmium telluride (CdTe)?

Cadmium telluride (CdTe) has a thermal conductivity of 6.2 W·m/m2·K. The source and test conditions are listed in the properties table on this page.

What is the coefficient of thermal expansion of Cadmium telluride (CdTe)?

Cadmium telluride (CdTe) has a coefficient of thermal expansion of 0.0000059 /K. The source and test conditions are listed in the properties table on this page.

What is the melting point of Cadmium telluride (CdTe)?

Cadmium telluride (CdTe) has a melting point of 1,041 °C. The source and test conditions are listed in the properties table on this page.

What is the Young's modulus of Cadmium telluride (CdTe)?

Cadmium telluride (CdTe) has a Young's modulus of 52 GPa. The source and test conditions are listed in the properties table on this page.

What is Cadmium telluride (CdTe) used for?

Uses recorded in the sources include Utility-scale thin-film PV plants; Thin-film PV panels made in the United States; Thin-film photovoltaic market share (market context, not one device).

Why it exists

Cadmium telluride (CdTe) is a semiconductor that absorbs sunlight in thin-film solar modules. Wikipedia gives its band gap as 1.5 eV at 300 K. Its importance comes from the module business: First Solar makes CdTe thin-film modules at scale, and Wikipedia says CdTe held 5.1% of worldwide PV production in 2013.

Where it's used

Utility-scale solar plants

Wikipedia lists Agua Caliente, Arizona at 290 MW and Topaz Solar Farm, California at 550 MW, whose construction finished in November 2014.

U.S. manufacturing

USGS reports that the leading domestic CdTe solar-panel maker began production at a fifth facility in mid-2025, with capacity expected to reach about 14 gigawatts per year once ramped up in 2026.

Market share

Wikipedia says CdTe held 5.1% of worldwide PV production and more than half of the thin-film market in 2013.

Recipe

CdTe

CdTe is a compound of one cadmium atom and one tellurium atom per formula unit, in the zinc-blende crystal structure. Wikipedia prints a molar mass of 240.01 g/mol and says CdTe is commercially available as a powder or as crystals, and can be made into nanocrystals. The page names only one production technique, growth of single crystals by HPVB and HPVZM methods.

What CdTe is made of
IngredientShare of the weightWhat it does
Cadmium Cd not stated The cadmium half of the lattice. Cadmium is a toxic element, and CdTe carries the GHS codes listed in the risks section.
Tellurium Te not stated The tellurium half of the lattice. Tellurium is recovered mainly as a byproduct of copper refining, according to the USGS.

Weight shares are as printed in the sources.

What it can do

Band gap

1.5 eV

measured

Wikipedia gives a direct band gap of 1.5 eV at 300 K, which it relates to a band-gap wavelength of about 830 nm.

Cell efficiency

22.1%

Wikipedia reports a record CdTe cell efficiency of 22.1% in February 2016, credited to First Solar.

Module efficiency

Up to 19.3%

First Solar lists its Series 7 module at up to 19.3% efficiency. This is a manufacturer headline, not a measured test with a stated method.

Ageing

0.3% per year

First Solar warrants an annual degradation rate of 0.3% and a 30-year linear performance warranty.

High-temperature output

5 to 9% more energy

Wikipedia says CdTe modules lose about half the performance of crystalline silicon modules at high temperature, yielding 5 to 9% more annual energy.

How it compares

Cadmium telluride is a thin-film semiconductor, and the sources collected here compare it mainly with crystalline silicon. Wikipedia says CdTe modules lose about half the performance of crystalline silicon modules at high temperature, yielding 5 to 9% more annual energy. The USGS says CdTe solar panels compete with crystalline silicon panels. No silicon band gap or silicon efficiency was read in this run, so the comparison stops at what these sources print.

The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Compare every grade in the family.

Benchmarks
MeasurementCdTe
Thermal behavior and safety
melting point1041 °C1
Thermal conductivityInfobox value, unit as printed on the page6.2 W·m/m2·K
specific heat210 J/kg·K3
Physical and electrical
DensityValue in the Wikipedia infobox5.85 g·cm−3
Other measurements
boiling point1050 °C2
Thermal expansion (CTE)5.9×10^-6 /K4
elastic modulusPrinted value for Young's modulus52 GPa
poissons ratioPrinted value for the Poisson ratio0.41 -
refractive indexInfobox value, labelled nD on the page2.67 -
Band gap1.5 eV5
Electron mobilityValue printed in the Applications section1100 cm²/V·s6
Hole mobilityValue printed in the Applications section100 cm²/V·s7
Solubility in water< 0.1 mg/L8
Lattice constantInfobox value, printed as a = 0.648 nm0.648 nm9
Molar massInfobox value240 g/mol10

Why choose it, and why not

Good for

  • Utility-scale thin-film PV: Wikipedia lists plants of 290 MW and 550 MW built with CdTe modules.
  • High-temperature energy yield: Wikipedia says CdTe modules yield 5 to 9% more annual energy than crystalline silicon at high temperature.

Watch out for

  • Cadmium toxicity: Wikipedia prints H302, H312, H332, H410 and H411 for CdTe, and a NIOSH limit of 0.005 mg/m3 as Cd.
  • Tellurium supply: the USGS lists tellurium as critical and says China produced 80% of estimated 2025 global output.
  • Efficiency figures: 22.1% is a laboratory record cell, and 19.3% is a manufacturer headline for the Series 7 module, not a field result.

CdTe is a mature thin-film absorber, backed by utility-scale plants and a manufacturer warranty of 0.3% per year degradation. Its main drawbacks are cadmium toxicity and a tellurium supply tied to copper refining. No source in this profile supports a space-flight or radiation-tolerance claim.

Technical details

For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.

Cell-level benchmarks

Values for finished cells. These vary by manufacturer, so read the conditions in the notes. Compare every grade in the family.

Cell-level benchmarks
MeasurementCdTe
Other measurements
Record CdTe cell efficiency22.1 %11
Module efficiency, Series 7< 19.3 %12
Warranted annual degradation rate0.3 %/year13

Notes

The method, full conditions and any caveat for the numbered rows above.

Notes for the numbered rows
#MeasurementMethodConditionsCaveat
1melting pointInfobox value, printed as 1,041 °C (1,906 °F; 1,314 K)pressure not printed on the page—
2boiling pointInfobox value, printed as 1,050 °C (1,920 °F; 1,320 K)pressure not printed on the page—
3specific heatInfobox value for heat capacity (C), unit as printed on the pagetemperature 293 K—
4Thermal expansion (CTE)Printed on the page as 5.9×10−6/K; written here in the file's exponent formtemperature 293 K—
5Band gapInfobox value. The page relates it to a band-gap wavelength of about 830 nmtemperature 300 Kgap type direct, printed as @300 K, directNot in spores/property-canon.yaml; short snake_case name used.
6Electron mobility—basis printed with a tilde (~1100 cm2/V·s) in a radiation-detector contextNot in spores/property-canon.yaml. Approximate, as printed.
7Hole mobility—basis printed with a tilde (~100 cm2/V·s) in a radiation-detector contextNot in spores/property-canon.yaml. Approximate, as printed.
8Solubility in waterFootnote to the infobox: the insoluble classification rests on a value below 0.1 mg/Ltemperature not printed on the pageNot in spores/property-canon.yaml.
9Lattice constant—temperature not printed on the pageNot in spores/property-canon.yaml.
10Molar mass—basis molar mass of the compound as printedNot in spores/property-canon.yaml.
11Record CdTe cell efficiencyPrinted on Wikipedia with the company and date; not re-measured herebasis record CdTe cell, laboratorydate February 2016maker First SolarNot in spores/property-canon.yaml.
12Module efficiency, Series 7Manufacturer product-page headline; a marketing figure with no test method statedbasis printed as 'Up to 19.3%' efficiencyproduct First Solar Series 7 CdTe moduleNot in spores/property-canon.yaml.
13Warranted annual degradation rateManufacturer warranty figure, not a measured field resultbasis manufacturer warranty rate, printed as 0.3% per yearproduct First Solar Series 7 CdTe moduleNot in spores/property-canon.yaml.

Corrosion and compatibility

What happens when it meets other materials and environments.

Corrosion and compatibility
EnvironmentConcernWhat happens
Outdoor field operation of a thin-film module (ageing) low First Solar warrants 0.3% per year degradation and a 30-year linear performance warranty.1
High operating temperature (module output) low Wikipedia says CdTe modules yield 5 to 9% more annual energy than crystalline silicon at high temperature.2
Corrosion details
#EnvironmentDetailsTest conditions
1 Outdoor field operation of a thin-film module (ageing) The Series 7 product page prints a 'Warranted Annual Degradation Rate' of 0.3% per year and a '30 Year Linear Performance Warranty'. Wikipedia says PV modules last 25 to 30 years. These are a manufacturer warranty and a general statement, not a measured field test. basis manufacturer warranty figureproduct First Solar Series 7 CdTe module
2 High operating temperature (module output) The page prints: CdTe modules lose about half the performance of crystalline silicon modules at high temperature, yielding 5–9% more annual energy. The page gives no test temperature or conditions for this statement. comparison crystalline silicon modulestemperature high temperature, not defined on the page

Risks and side effects

Hazards to people, what happens when a cell overheats, and how the material is handled and stored.

For people

Wikipedia prints GHS hazard codes for CdTe and a NIOSH limit for cadmium. It does not give a verdict on the powder.

The compound
Wikipedia prints the GHS hazard codes H302, H312, H332, H410 and H411 for CdTe, under the signal word Warning. A Kurt J. Lesker safety data sheet for the same CAS number prints H302, H312, H332, H400 and H410, also under the signal word Warning.
Exposure limit
NIOSH lists 0.005 mg/m3 as Cd as a time-weighted average permissible exposure limit, and an IDLH of 9 mg/m3 as Cd.

If a module overheats

These results come from laboratory heating tests and from air-emission figures on Wikipedia, not from field incidents.

Lab heating
In lab tests at about 1100 °C, 0.4 to 0.6% of the cadmium content was released, according to Wikipedia.
Air emissions
Wikipedia prints cadmium air emissions of 0.02 to 0.5 grams per GWh of PV electricity.

Handling and storage

Dust
Keep airborne cadmium below 0.005 mg/m3 as Cd, the NIOSH limit printed on Wikipedia.
Recycling
First Solar recovers up to 95% of semiconductor material and 90% of glass from end-of-life modules, per Wikipedia.
Water
Wikipedia gives CdTe as insoluble in water, with a footnote placing the basis below 0.1 mg/L.

Test details
The original wording and numbers from the sources, for readers who want them.

Failure risks

Failure risks
FailureTrigger and consequence
Cadmium release at high temperaturemoderate severityLaboratory heating at about 1100 °C0.4 to 0.6% of the cadmium content was released in these lab tests (Wikipedia prints 0.4–0.6%).

Side effects on surrounding parts

Side effects on surrounding parts
AffectsEffect
Air around the plant and its surroundingsCadmium air emissions: 0.02 to 0.5 grams per GWh of PV electricity, as printed on Wikipedia.

Handling and storage

  • First Solar recovers up to 95% of semiconductor material and 90% of glass from end-of-life modules, per Wikipedia. Its recycling program began in 2005.

Mitigations

  • Keep airborne cadmium below the NIOSH permissible exposure limit of 0.005 mg/m3 as Cd, as printed on Wikipedia.

Supply and geography

How common the raw materials are and where they come from.

Cadmium

The USGS gives the cadmium content of typical zinc ores as about 0.03%, and says cadmium is generally recovered from zinc ores. A crust abundance was not found in the sources read.

Top producers (2025)
China 41.3%, Korea, Republic of 18.7%, Canada 5.7%
Critical mineral lists
US: not listed, EU: not listed
Recycling
USGS: secondary cadmium is mainly recovered from spent NiCd batteries, and CdTe solar panels are named among the scrap from which cadmium can be recycled.
Substitutes
USGS: batteries with other chemistries, particularly lithium-ion, can replace NiCd batteries, and zinc-nickel coatings can replace cadmium in many plating applications.

Tellurium

Wikipedia says tellurium's abundance in the Earth's crust is comparable to platinum's. No numeric crust abundance was read in this run.

Top producers (2025)
China 80%, Japan 6.1%, Canada 2.8%
Critical mineral lists
US: listed, EU: not listed
Recycling
USGS: tellurium was recycled from CdTe solar cells in the United States, but the quantity was limited because most of those cells had not reached the end of their useful life.
Substitutes
USGS: amorphous silicon and copper indium gallium diselenide are the two principal competitors with CdTe in thin-film photovoltaic cells.

Updated