LG Display has deployed high mobility oxide (HMO) thin-film transistor technology and supporting equipment on its sixth-generation small and mid-size OLED production line, The Elec reported June 1, as Apple evaluates HMO as the low-power successor to the LTPO (low-temperature polycrystalline oxide) backplane used in current wearables and smartphones. Industry sources confirm the Gen-6 line is now running development and verification — a signal that the next major transition in Apple display technology has moved from research into active production preparation.
Apple Watch panels are expected to be the first commercial application, with an industry source telling The Elec that LG Display plans to supply HMO-based smartwatch panels starting in 2027. The timetable aligns with Apple's established pattern of validating new backplane technologies through wearables before extending them to mobile and IT devices such as iPhones and iPads.
What High Mobility Oxide Displays Solve
HMO addresses the central weakness of conventional oxide TFTs: electron mobility that is too low to drive high-resolution, high-refresh-rate OLED displays. Current mass-produced oxide TFTs deliver electron mobility at or below 10 cm²/Vs — a figure the industry regards as insufficient for next-generation IT OLEDs. The target for those applications sits between 30 and 50 cm²/Vs, a three- to five-fold improvement that HMO is designed to deliver.
Oxide TFTs already hold a structural advantage over their LTPS and LTPO counterparts in one key dimension: they do not require laser crystallization or ion implantation, two process steps that add manufacturing complexity and cost. That simplified process flow makes oxide-based backplanes inherently cheaper and more power-efficient at low refresh rates. LTPO, the backplane Apple currently uses in its Pro iPhones and all Apple Watch models, combines LTPS's high electron mobility with oxide's low off-current to achieve variable refresh rates down to 1Hz — enabling the always-on display feature without heavy battery drain. HMO aims to reach LTPS-comparable mobility entirely within the oxide material system, eliminating the need for LTPS altogether.
LG Display Sputtering vs Samsung Display ALD: Competing Paths to HMO
The two Korean display giants are pursuing HMO through different deposition methods. LG Display is using sputtering — a thin-film deposition technique already standard in oxide processes — on its Gen-6 line. The choice lets LG Display reuse existing mass-production equipment and integrate HMO development into its current infrastructure, lowering the barrier to line conversion if verification succeeds.
Samsung Display is taking a different route on its Gen-8.6 line, where it reportedly applies atomic layer deposition (ALD) — a process that offers tighter control over film composition and higher achievable mobility. The tradeoff is a narrower process window that industry observers have flagged as a yield and stabilization challenge.
Both methods face the same core obstacle: simultaneously achieving high electron mobility, large-area uniformity, and long-term reliability in a backplane suitable for mass production. Raising mobility in oxide semiconductors can introduce threshold voltage instability under sustained operating stress — a failure mode the display industry has studied in amorphous indium-gallium-zinc-oxide (IGZO) TFTs and is working to engineer around through materials choices and device architecture.
LG Display has an additional motivation to move quickly on this front. Following Japan Display Inc.'s exit from the Apple Watch OLED panel market in late 2025, LG Display became the sole supplier for the entire Apple Watch lineup — a position that gives it a direct commercial incentive to stay ahead of the next backplane transition.
LTPO Successor Backplane: Apple's Dual-Source Strategy
Apple does not single-source display technologies. According to The Elec, Apple has historically validated new backplane approaches with LG Display on Apple Watch first, then expanded development requests to both LG Display and Samsung Display as a technology moves toward iPhone adoption. HMO is following the same path — Apple is evaluating both suppliers for the eventual mobile rollout, and the technology is being considered not only for wearables but also for IT OLED products including tablets and laptops.
That dual-source dynamic shapes how much weight any single supplier's verification progress carries. LG Display's Gen-6 HMO work does not guarantee it will supply HMO panels for iPhones; it establishes LG Display as a credible candidate when Apple decides to scale. Final product lineup and commercialization timing remain subject to Apple's schedule decisions and the outcome of equipment verification on both sides.
Apple Watch Battery Life Display Technology: What Mass Production Still Requires
LG Display's Gen-6 verification is a necessary precondition for mass production, not a completion of it. The company must still confirm that its sputtering-based HMO process delivers acceptable electron mobility at production-scale substrate sizes, maintains uniformity across the full panel area, passes long-term reliability testing under operating stress, achieves adequate production yield, and meets the process temperature budget for the Gen-6 line. None of these parameters are assured by the installation of development equipment alone.
The exact date on which LG Display began its HMO verification program has not been publicly disclosed. Whether HMO panels reach Apple Watch models in 2027 depends on both LG Display's internal verification results and Apple's own qualification schedule — and Apple has shown, in the LTPO transition and the aborted microLED Apple Watch program, a willingness to extend timelines when a technology is not ready.
Frequently Asked Questions
What is high mobility oxide display technology?
High mobility oxide (HMO) is a thin-film transistor backplane design that aims to raise the electron mobility of oxide-based TFTs from the current mass-production ceiling of around 10 cm²/Vs to the 30–50 cm²/Vs range needed for high-resolution, high-refresh-rate OLED displays. Because oxide TFTs do not require the laser crystallization steps that LTPS requires, an HMO-based backplane would combine low manufacturing cost with the high switching speeds currently only achievable through hybrid LTPO designs.
How does HMO differ from LTPO in Apple devices?
LTPO backplanes combine two transistor types — LTPS for high-current driving and oxide for low-current switching — to achieve variable refresh rates between 1Hz and 120Hz. HMO replaces that hybrid architecture with a pure oxide design that targets LTPS-level electron mobility, potentially eliminating the LTPS component entirely and simplifying both the manufacturing process and the power management circuit. Apple's current Pro iPhones and all Apple Watch models use LTPO.
When will Apple Watch get HMO display technology?
An industry source told The Elec that LG Display plans to supply HMO-based Apple Watch panels starting in 2027, contingent on successful verification of its Gen-6 sputtering process. Apple has not confirmed any product timeline; commercial adoption will depend on both supplier verification results and Apple's own qualification schedule.
Why is LG Display using sputtering instead of ALD for HMO backplane development?
Sputtering is already the standard deposition method in LG Display's existing oxide TFT manufacturing lines, which means the company can run HMO development on its current Gen-6 infrastructure without replacing or reconfiguring its core equipment. Samsung Display is pursuing ALD on its Gen-8.6 line, a method that can achieve higher electron mobility but has a narrower process window and is associated with yield and stabilization challenges at scale.
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