OLED screens and LCD screens are two different screens used in iPhone phones. The main difference between the two is the difference in the way they emit light: LCD screens rely on backlight panels, which require red, green, and blue filters in front of a white backlight, separated by a liquid crystal layer, and then a polarizing plate and glass substrate, which is thicker overall, about 0.6-0.8 mm; OLED screens use organic compounds, which can emit red, green, and blue light on their own when electricity passes through them.
OLED screen uses organic compound, when the current passes, the sub-pixel can emit red, green, blue light by itself, no need to add additional backlight board and filter, and no need for liquid crystal layer, only a polarization layer, the thickness can be 0.3 mm.
OLED screens allow pixel-level control of color, so color accuracy is nearly perfect and almost indistinguishable to the naked eye; because they can express 100% black by extinguishing pixel dots, OLED screens theoretically have nearly infinite contrast; the latest iPhone 11 Pro series, the screen brightness can reach 800 nits, ensuring that even in midday sun, the screen content can be clearly displayed.
LCD screens are slightly less accurate and contrasted because the color brightness can only be adjusted by the backlight panel as a whole, plus the LCD deflection does not achieve 100% shading, and there is a slight error in the color expression of each pixel point.
OLED has a faster switching speed (the time it takes for each pixel to completely change color) than LCD. The best LCD displays can completely switch colors in milliseconds (thousandths of a second), while the best OLED displays can completely switch colors in just a few microseconds (millionths of a second), and there is less chance of blurred content or trailing when playing games or dynamic video content.
OLED can save power by cutting off the power supply to the pixel when the pixel does not express itself (e.g. black), while LCD screens can only save energy by reducing the overall brightness of the screen, which is relatively inefficient.