OLED smartphones are emerging as the differentiator in the saturated smartphone industry worldwide. More and more flagship smartphones are beginning to adopt OLED panels to seek for differentiation in terms of design (internal and external) and power consumption. Samsung has been leading this market so far, and captured no.1 spot in many of major countries including USA and South Korea. Apple joined this market with its first OLED iPhone X from Q4 2017, and rose to no.1 vendor in Japan. Our HCST service starts to track OLED smartphone volume and market share by major vendors for five countries, the US, China, India, Japan and South Korea.