TCL has come under scrutiny this month after testing that claimed to examine three TCL TVs marketed as quantum dot TVs reportedly showed no trace of quantum dots.

Quantum dots are semiconductor particles that are several nanometers large and emit different color lights when struck with light of a certain frequency. The color of the light emitted by the quantum dot depends on the wavelength, which is impacted by the quantum dot's size. Some premium TVs (and computer monitors) use quantum dots so they can display a wider range of colors.

Quantum dots have become a large selling point for LCD-LED, Mini LED, and QD-OLED TVs, and quantum dot TVs command higher prices. A TV manufacturer pushing off standard TVs as quantum dot TVs would create a scandal significant enough to break consumer trust in China's biggest TV manufacturer and could also result in legal ramifications.

But with TCL sharing conflicting testing results, and general skepticism around TCL being able to pull off such an anti-consumer scam in a way that would benefit it financially, this case of questionable colorful TVs isn't so black and white. So, Ars Technica sought more clarity on the situation.

Tests unable to detect quantum dots in TCL TVs

Earlier this month, South Korean IT news publication ETNews published a report on testing that seemingly showed three TCL quantum dot TVs, marketed as QD TVs, as not having quantum dots present.

Hansol Chemical, a Seoul-headquartered chemicals company, commissioned the testing. SGS, a Geneva-headquartered testing and certification company, and Intertek, a London-headquartered testing and certification company, performed the tests.

The models examined were TCL's C755, said to be a quantum dot Mini LED TV, the C655, a purported quantum dot LED (QLED) TV, and the C655 Pro, another QLED. None of those models are sold in the US, but TCL sells various Mini LED and LED TVs in the US that claim to use quantum dots.

According to a Google translation, ETNews reported: “According to industry sources on the 5th, the results of tests commissioned by Hansol Chemical to global testing and certification agencies SGS and Intertek showed that indium... and cadmium... were not detected in three TCL QD TV models. Indium and cadmium are essential materials that cannot be omitted in QD implementation.”

The testing was supposed to detect cadmium if present at a minimum concentration of 0.5 mg per 1 kg, while indium was tested at a minimum detection standard of 2 mg/kg or 5 mg/kg, depending on the testing lab.
 

TCL’s response

In response to the results from SGS and Intertek, a TCL representative told ETNews and The Korea Times that TCL is "manufacturing TV sets with QD films supplied by three companies" and that "the amount of quantum dots... in the film may vary depending on the supplier, but it is certain that cadmium is included."

TCL also published testing results on May 10 commissioned by Guangdong Region Advanced Materials, one of TCL's quantum dot film suppliers. Interestingly, SGS, one of the companies that found that TCL's TVs lacked quantum dots, performed the tests. This time, SGS detected the presence of cadmium in the TV films at a concentration of 4 mg/kg (an image of the results can be seen via ETNews here).

TCL also said that it "confirmed the fluorescent characteristics of QD," per Google's translation, and provided a spectrogram purportedly depicting the presence of quantum dots in its TVs' quantum dot films.

Why the differing results? One likely reason is the difference in testing methods. The tests that found cadmium examined TCL's quantum dot film supplies. The Hansol-commissioned tests, however, looked at quantum dot films on finished TCL TVs. Some propose that testing final products would be a better way to determine quantum dot quantities.

TCL disagrees with this notion, though, and questioned the Hansol-commissioned tests' methods and accuracy. A company rep claimed that the tests would be unable to "detect the exact content of cadmium," per Google's translation. However, there's reason to be skeptical about results provided by TCL and commissioned by a TCL partner regarding TCL products.

It's also possible that the negative results were related to damaged quantum dot films, although such damage could notably impact a TV's image. I asked Eric Virey, principal displays analyst at Yole Intelligence, about this, and he noted that it's "possible that quality control at some of TCL's QDEF [quantum dot enhancement film] is subpar and that the concentration of quantum dots is not homogeneous from one batch to another, or even within a single TV.

"That wouldn’t speak very highly of TCL’s own quality control but wouldn’t necessarily mean that there is an intention to deceive the consumers," Virey said.

When asked which testing method is more accurate for determining if TCL's QD-branded TVs use quantum dots, Virey said the superior test would not be about measuring their exact concentration but, rather, testing TV performance to see if the products meet the specifications, like color gamut and brightness, claimed.

"If not, there might be a clear intention to deceive, which I personally think is unlikely," Virey said.

I looked around, but with the TVs not being released in the US and other geographies, detailed reviews/performance testing weren't readily available.

A question of cadmium

For a better understanding of this situation, a broad overview of the use of cadmium in quantum dot displays may be helpful.

TCL claims that its QLED and quantum Mini LED TVs use cadmium but makes no mention of indium. For those wondering, you don't need both for a TV to qualify as a quantum dot TV. Per Virey, some quantum dot displays are "pure QD-based," while others "are a mix of QDs (indium and/or cadmium) and phosphors, which is an entire different class of material but used for the same purpose of converting blue light from the LEDs into red and green."

In an email to Ars, Virey explained that in a TV that combines quantum dots and phosphor, "the amount of QDs can indeed be much lower (less than 1/10th)." That wouldn't show up on the Hansol-commissioned tests, which had cadmium minimum detection standards of 0.5 mg/kg. Per Virey:

That type of design is cheaper to produce, although not by much, but [of] course, delivers lower performance in terms of color gamut, color purity, and brightness. It’s very likely that TCL uses this type of designs for its entry-level QLED TVs.

It's also worth noting that the European Union's Restriction on Hazardous Substances (RoHS) limits the amount of cadmium permitted in electronics sold in the EU. Per the EU law, the maximum concentration value of cadmium permitted is generally 0.01 percent by weight. However, there are exemptions, including one allowing for a higher concentration (0.2g per square meter) in displays. Still, most quantum dot displays either don't use cadmium at all or only use a very small quantity. Samsung, for example, boasts about only using cadmium-free quantum dots.

As Display Daily reported in February, most companies already use less than 0.01 percent by weight of cadmium "either by optimizing the amount of cadmium in their [cadmium selenide] QDs or by substituting with [indium phosphide] QDs."

"In many cases the films contain 0 [parts per million] cadmium. The same is true for extruded QD diffusers (x-QDEF) where, in theory, CdSe or InP could be used," the publication said.

Hansol bias suspected

TCL obviously has reason to try to push results that show the presence of cadmium. However, some analysts and publications have pointed out that Hansol could have reason to push results claiming the opposite.

As mentioned above, Hansol is in the chemical manufacturing and distribution business. It notably does not sell to TCL but does have a customer in TCL rival Samsung.

Taking a step back further, Hansol is headquartered in Seoul and is considered a chaebol. TV giants Samsung and LG are also chaebols, and the South Korean government has reported interest in Samsung and LG continuing to be the world's biggest TV companies—titles that are increasingly challenged by Chinese brands. It has previously been reported that the South Korean government urged Samsung and LG to meet with each other to help ensure their leadership. The talks resulted in a partnership between the two companies reportedly centered on counteracting high prices that Samsung was facing for TV components sold by Chinese companies.

With this background in mind, Hansol could be viewed as a biased party when it sought testing for TCL quantum dot TVs.