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CPL is an auxiliary layer that corrects optical properties to increase light efficiency. It is made on the cathode of OLED. CPL reduces light loss that occurs during the reflection process of light emitted from the OLED emission layer by the upper and lower electrodes (cathode and anode) and helps the light to be directed towards the display.
Until now, only high-refractive index CPL has been applied to iPhone OLEDs. However, applying low-refractive index CPL together increases light efficiency. By alternately stacking thin films with different refractive indices than when using only high-refractive index CPL, light scattering in all directions can be further reduced, improving front luminance and power consumption efficiency. This is why Samsung Display and LG Display have developed OLEDs that apply both high-refractive index CPL and low-refractive index CPL.
An industry insider A said, "For the past 2~3 years, Samsung Display and LG Display have proposed OLEDs with added low-refractive index CPL to Apple, but Apple decided not to apply low-refractive index CPL even to the iPhone 18 series OLEDs to be released this year." He added, "Adding low-refractive index CPL increases the process and inevitably leads to an increase in manufacturing costs."
To add existing high-refractive index CPL to low-refractive index CPL, it must be stacked in the order of 'low-refractive index CPL - high-refractive index CPL - low-refractive index CPL'. Apple, which needs to lower manufacturing costs due to the recent rise in memory semiconductor prices, seems to have judged that the cost increase compared to the utility of adding low-refractive index CPL is low.
Another insider B said, "Apple's decision not to apply low-refractive index CPL to the iPhone 18 series OLEDs may be due to the technological capabilities of one of the two domestic panel companies." He explained, "Apple often applies a particular technology when two or more vendors can stably mass-produce it."
▶ Original source: https://zdnet.co.kr/view/?no=20260728003120
