The sales of iPhone X turned out to be less than market expectation, so Samsung has lowered the utilization rate of OLED production lines. The tight supply of OLED panels over the past two years has also been eased. According to WitsView, a division of TrendForce, Apple has initiated the trend of OLED panels, and it is estimated that the penetration rate of OLED panel in smartphones will reach 46% by 2021. Mini LED is overwhelmed by OLED’s technology maturity and competitive costs, so it might be hard for Mini LED to grow in the smartphone market in short term.

(Image: Samsung)

WitsView points out that, current supply of OLED panel from Samsung was occupied by iPhones and high-end Samsung smartphones, while the yield rate of other OLED panel makers remains low. As the result, mobile phone vendors have been trying to find alternatives for their flagship models. Mini LED is considered a feasible option because it is comparable to OLED in terms of high color saturation, high contrast, and support to HDR. However, the advantages of OLED are more obvious.

OLED can be thin, light and bendable as it does not need backlight

In addition to high color saturation, high contrast, and fast response time, the biggest advantage of OLED panels is its features of self-emitting and bendable, allowing phone vendors to be more flexible in thickness and appearance design of phones. Mini LED can serve as a transitional product before micro LED is fully ready to enter mass production. With the original LCD structure unchanged, the size of LED chips is reduced to 100 to 300 micrometers, and the LEDs are placed in the backlight modules through the matrix arrangement method. In 5.5-inch FHD display, for example, the number of LEDs used is as high as 2,000-10,000. Smaller number of LEDs needs longer optical distance, making the devices thicker. The large number of LEDs can reduce the required optical distance and improve the uniformity, making the entire device thinner, but will cause heat dissipation problems and make the cost higher. As present, how to achieve the balance remains the bottleneck for manufacturers.

Mini LED should target at niche market

From the perspective of costs, OLEDs are more competitive in current stage. Taking a 5.5-inch hard OLED panel as an example, the cost is around US$17~18; but for a Mini LED backlight panel of the same size and the same resolution, the costs may double and reach US$35~40. As the tight OLED supply being released, WitsView believes that the quotes for OLED smartphone panels will be relatively weak in the long-term, the price cuts of LTPS panels will also bring more pressure to Mini LED. Therefore, it will be difficult for Mini LED to compete with OLED panels in high-end smartphone market if Mini LED cannot reduce the costs.

The cost of using Mini LED in smartphone backlighting depends on the number of LED chips used and the transfer efficiency of wafer. Therefore, many LED manufacturers try to lower the costs through different technical solutions, such as reducing the number of LED chips by optical adjustment, or increasing the transfer efficiency of die bond machines to reduce the cost of bonding.

However, in the more profitable niche markets where the gross profits are high, the costs are not a priority for vendors. Therefore, Mini LED has higher chance to be adopted in the niche markets. Current devices using Mini LED include the 10.1-inch automotive display released by Innolux at the CES 2018, the 27-inch LCD gaming monitor, 15.6-inch notebook and 2-inch VR devices launched by AUO recently, etc. it can be seen that the Mini LED technology has more opportunities in niche markets.