Stacks of Opinions (on Stacks)
We have noted recently that Samsung Display (pvt) has had differing opinions about an OLED technology called ‘tandem’ or ‘dual stack’ structure. In typical smartphone OLED displays the OLED materials, particularly the emissive OLED materials are arranged in layers between an anode and a cathode, with three (Red, Green, Blue) sub-pixels making up a single pixel that can display millions of colors by varying the mix of the three. The key process for producing OLED displays is deposition where the materials are heated in a vacuum until they vaporize and then settle on a substrate after passing through a mask that patterns them into sub-pixel ‘dots’. In an OLED display a backplane of thin-film transistors (TFT) control each subpixel by providing a ‘push’ that causes the materials to produce light and create a full color image.
OLED materials are relatively complex and are continually being developed to increase their efficiency and light output, but said materials have some limitations such as a point at which applying more ‘push’ does not generate more light and can degrade the materials more quickly. This limits OLED display ‘brightness’ relative to non-emissive displays that use a backlight to generate brightness, which has led some to criticize OLED display technology as ‘not bright enough’. While new OLED materials continue to push those limitations, a number of OLED panel producers have been developing a new OLED structure that places two OLED stacks on top of each other, creating a brighter display, but there has been some controversy among suppliers as to whether this approach is a viable one for OLED displays.
LG Display (LPL) is the only OLED display supplier to have the production capabilities to produce such tandem OLED displays and uses them for automotive displays that must meet strict brightness specifications, however Apple is looking to incorporate such an OLED solution in products in order to quell potential brightness issues in a number of its products, particularly tablets and laptops. As Apple’s largest OLED display supplier is Samsung Display, SDC was charged with developing a dual-stack OLED 11.9” display for a potential iPad product but said project was cancelled in 3Q last year, reportedly as SDC could not find a way to produce such a display economically given the additional process steps and process modifications needed for the new structure. However, as we recently noted, SDC decided to get back into ‘Dual Stack’ development, likely as China’s BOE (200725.CH) has indicated that it is modifying some of its OLED capacity to produce dual-stack displays.
But all is not rosy even for BOE, who has recently become a 3rd supplier of OLED displays to Apple after an arduous qualification process., as there is another aspect to Apple’s desire to implement a tandem stack OLED structure in future products, and that is the backplane that controls the OLED pixels. There are two competing control structures that are used in OLED displays, LTPS (Low Temperature Polysilicon) and LTPO (Low Temperature Poly-Oxide), with the former the most common. LTPO however is Apple’s choice for its premium iPhones and will likely push to expand LTPO’s use across more products as it requires less power, improving battery life in mobile devices. Samsung Display has been Apple’s primary LTPO OLED display supplier, with LGD beginning to compete in that arena, but BOE does not have sufficient LTPO capacity to provide a dual stack device using LTPO in the quantities needed by Apple.
According to South Korean trade press, BOE was in talks to supply a tandem OLED display to Chinese smartphone brand Honor (pvt) but rejected the brand’s request for that device to also incorporate LTPO under the theory that while the dual-stack structure could reduce the power consumption of the device by 30%, the application of an LTPO backplane would not add enough additional power savings to make it worthwhile to produce. On the surface that seems plausible however given BOE’s lesser experience with LTPO production we expect the allocation of resources to building out their LTPO production and their dual stack initiative might have proved to be a bit more than BOE was willing to take on, particularly as the dual stack structure requires two deposition lines instead of one or a 50% reduction in capacity if the same deposition line is used for both stacks.
Apple is certainly a demanding partner to display producers but with unit volumes at or near the top of the industry and a willingness to pay a premium for cutting edge technology, the company represents a massive source of revenue over time, albeit not without risk and/or cost. If Samsung Display was willing to change their mind about a dual stack structure, likely at Apple’s behest, than we expect BOE might also decide that the opportunity is too lucrative to miss sometime in the near future, especially as Samsung Display is not the leader in tandem OLED structure production, as they are in most other OLED display production modalities. We are still in the early stages of this horserace.
OLED materials are relatively complex and are continually being developed to increase their efficiency and light output, but said materials have some limitations such as a point at which applying more ‘push’ does not generate more light and can degrade the materials more quickly. This limits OLED display ‘brightness’ relative to non-emissive displays that use a backlight to generate brightness, which has led some to criticize OLED display technology as ‘not bright enough’. While new OLED materials continue to push those limitations, a number of OLED panel producers have been developing a new OLED structure that places two OLED stacks on top of each other, creating a brighter display, but there has been some controversy among suppliers as to whether this approach is a viable one for OLED displays.
LG Display (LPL) is the only OLED display supplier to have the production capabilities to produce such tandem OLED displays and uses them for automotive displays that must meet strict brightness specifications, however Apple is looking to incorporate such an OLED solution in products in order to quell potential brightness issues in a number of its products, particularly tablets and laptops. As Apple’s largest OLED display supplier is Samsung Display, SDC was charged with developing a dual-stack OLED 11.9” display for a potential iPad product but said project was cancelled in 3Q last year, reportedly as SDC could not find a way to produce such a display economically given the additional process steps and process modifications needed for the new structure. However, as we recently noted, SDC decided to get back into ‘Dual Stack’ development, likely as China’s BOE (200725.CH) has indicated that it is modifying some of its OLED capacity to produce dual-stack displays.
But all is not rosy even for BOE, who has recently become a 3rd supplier of OLED displays to Apple after an arduous qualification process., as there is another aspect to Apple’s desire to implement a tandem stack OLED structure in future products, and that is the backplane that controls the OLED pixels. There are two competing control structures that are used in OLED displays, LTPS (Low Temperature Polysilicon) and LTPO (Low Temperature Poly-Oxide), with the former the most common. LTPO however is Apple’s choice for its premium iPhones and will likely push to expand LTPO’s use across more products as it requires less power, improving battery life in mobile devices. Samsung Display has been Apple’s primary LTPO OLED display supplier, with LGD beginning to compete in that arena, but BOE does not have sufficient LTPO capacity to provide a dual stack device using LTPO in the quantities needed by Apple.
According to South Korean trade press, BOE was in talks to supply a tandem OLED display to Chinese smartphone brand Honor (pvt) but rejected the brand’s request for that device to also incorporate LTPO under the theory that while the dual-stack structure could reduce the power consumption of the device by 30%, the application of an LTPO backplane would not add enough additional power savings to make it worthwhile to produce. On the surface that seems plausible however given BOE’s lesser experience with LTPO production we expect the allocation of resources to building out their LTPO production and their dual stack initiative might have proved to be a bit more than BOE was willing to take on, particularly as the dual stack structure requires two deposition lines instead of one or a 50% reduction in capacity if the same deposition line is used for both stacks.
Apple is certainly a demanding partner to display producers but with unit volumes at or near the top of the industry and a willingness to pay a premium for cutting edge technology, the company represents a massive source of revenue over time, albeit not without risk and/or cost. If Samsung Display was willing to change their mind about a dual stack structure, likely at Apple’s behest, than we expect BOE might also decide that the opportunity is too lucrative to miss sometime in the near future, especially as Samsung Display is not the leader in tandem OLED structure production, as they are in most other OLED display production modalities. We are still in the early stages of this horserace.
The Epsom Derby - Source: Horseracingnation.com
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