The iPhone might start using double-layer OLEDs. Can it make it in time for the 20th anniversary?

Dual OLED

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According to foreign media Wccftech, Apple is considering bringing the double - layer OLED screen that amazed everyone on last year's iPad Pro to the iPhone.

However, don't get too excited just yet. Current news indicates that the double - layer OLED is expected to take at least 2 - 3 years to be actually implemented. At the earliest, it will have to wait until the 20th - anniversary iPhone the year after next.

Apple isn't the only one interested in the double - layer OLED screen. Domestic manufacturers such as Huawei and Honor have been exploring double - layer OLED products, including tablets and mobile phones, since last year.

The double - layer OLED screen is likely to become the standard for flagship mobile phones in the future.

Double - layer OLED: Bright and power - saving

The full name of "double - layer OLED" is double - layer tandem OLED technology. As the name suggests, it means stacking two or more layers of OLED light - emitting materials in series on a single screen.

Left: Single - layer OLED; Right: Double - layer OLED

The benefits are obvious. Since there is an extra layer of OLED light - emitting material, the peak brightness of the double - layer OLED is naturally higher than that of the traditional single - layer OLED.

In the low - brightness scenarios of daily use, the workload that was previously borne by one OLED light - emitting unit is now shared by two units. With the reduced workload, the power consumption is naturally much lower. Therefore, the lifespan of the double - layer OLED screen is longer than that of the single - layer OLED.

Also, because the two layers of OLED are connected in series, a higher electro - optical conversion efficiency can be achieved. Theoretically, in the daily use environment with mainly medium and high brightness, the screen power consumption will be lower.

That is to say, when using the phone outdoors or watching HDR content, the double - layer OLED can provide a better display effect and may also bring better battery life to the phone.

Comparison between the M4 iPad Pro (left) and the M2 iPad Air with an LCD screen (right). Image source: Reddit@Dance with Macaw

This technology is actually similar to the down - scaling of OLED stacking in the TV field. The G5 TV launched by LG this year uses a four - layer stacked screen. However, each panel is only responsible for the light source of one color, rather than the RGB arrangement, but the concept is similar. The biggest benefits are also brightness and lifespan.

LG G5. Image source: Tech Radar

Due to its ability to achieve high peak brightness and long lifespan, the double - layer OLED technology has actually been used by many automobile brands to build in - car display screens several years ago.

The Li MEGA and the 2024 L9 are both equipped with double - layer OLED in - car displays.

Since last year, we have finally been able to see this technology in mobile phones, tablets, and laptops.

The most well - known example is certainly the Apple M4 iPad Pro. It is probably the first time many people have heard of this technology.

The double - layer OLED on the iPhone is still in the rumor stage, while Huawei and Honor have taken the lead in bringing the double - layer OLED screen to their flagship mobile phones' top - end models.

The improvement is very obvious. The M4 iPad Pro promises a full - screen brightness of up to 1000 nits and a peak brightness of 1600 nits, which is an extremely high level for this size. Many actual tests have reached or even exceeded the stated data.

In an indoor environment, the brightness is locked at 500 nits. Outdoors, the full - screen brightness can reach 1000 nits, and the HDR brightness can exceed 1600 nits in a 50% window. Image source: digitec

The same situation also occurs on the Huawei Mate 70 RS. According to actual tests, the HDR peak brightness can reach 4000 nits, and the full - screen excitation brightness is also 2000 nits, which is almost the ceiling level for smartphones at present.

Behind these "glorious" actual performances, as a relatively new technology, the double - layer OLED still faces many challenges before it reaches more consumers.

Challenges in the implementation of double - layer OLED

The price of high - quality OLED materials is not low. It's easy to imagine the material cost of using two layers at once.

Integrating two layers of OLED light - emitting materials into the same screen requires precise alignment within an error of 5 µm, which is five times more difficult than aligning a hair. This is in itself a challenge in terms of craftsmanship. The low production volume naturally leads to a significant increase in cost.

The expensive double - layer OLED screens are naturally used in a small number of the most expensive models.

The Huawei Mate 70 RS Ultimate Design starts at 11,999 yuan.

Although using multiple OLED light - emitting layers can achieve twice the result with half the effort, it also magnifies the defects of the OLED screen itself, especially the issue of uniformity.

Do you still remember the "smudged screen" phenomenon of OLED screens in the early years, that is, the uneven performance of grayscale uniformity at low brightness?

The iPhone 12 screen had the common problem of a "smudged screen" back then. Image source: YouTube@KDCloudy

The reason for the "smudged screen" is related to the characteristics of the OLED screen itself. When the brightness or current is low, the stability of the OLED light - emitters also decreases. Due to the self - luminous characteristic, the brightness and color of each light - emitter will be inconsistent, resulting in a patchy appearance on the screen.

OLED is more sensitive to low current, resulting in instability. Image source: Ossila

Now, with two OLED layers, the uniformity is even more compromised. Whether it's the Honor Magic 6 RS or last year's Huawei MatePad Pro 12.2, there have been relevant complaints on social media.

To solve the problem of uneven brightness, besides locking the minimum brightness, the method of low - frequency dimming is also used. The cost is a "eye - straining screen", which places a greater burden on the eyes. This is also the strategy adopted by the iPad Pro.

The screen uniformity of the Huawei Mate 70 RS is higher. The industry believes that Huawei may have used the method of controlling the yield rate with instruments to improve the overall level of the shipped screens, and the cost will naturally soar.

Image source: PoorPlayers

The high material cost, high production difficulty, and low yield rate make it not so easy to promote the double - layer OLED screen. The Honor Magic 6 RSR was the first phone to use the double - layer OLED, but the next - generation model switched back to the traditional screen.

Interestingly, Apple is currently evaluating a brand - new double - layer OLED technology from LG, attempting to cleverly solve the challenges of cost and yield rate.

In the traditional double - layer OLED screen, both layers have a complete RGB array, containing red, blue, and green light - emitters.

Now, LG has introduced a brand - new double - layer architecture. One layer still retains the red, green, and blue light - emitters, while the other layer only has blue light - emitters. It is called a "partially tandem" or "simplified tandem" OLED.

Since the blue light has a short wavelength and high energy, the blue light - emitter in the OLED panel has the lowest luminous efficiency, the shortest lifespan, and the highest energy consumption.

Therefore, the simplified tandem OLED can be said to take advantage of the longer lifespan and lower energy consumption characteristics of this technology to target the blue light - emitter.

Compared with the complete double - layer tandem OLED, the partially tandem OLED only stacks a single color, which is easier to control in terms of craftsmanship and yield rate. It can greatly reduce the cost and is more suitable for mass - producing mobile phones. It is a solution that can achieve great results with little effort.

Schematic diagram of the simplified tandem OLED screen technology

Of course, compared with the complete double - layer tandem OLED, the partially tandem OLED is inferior in terms of brightness, especially the extreme brightness, and color uniformity. However, it is a more worthwhile trade - off and is expected to allow more people to enjoy this good screen.

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