# **Differences of OLED screens** **OLED, AMOLED and POLED are developed on the same technology platform but have their own characteristics. In addition, there are many factors that affect display quality.** OLED screens are common on newer phones, tablets, smartwatches, laptops and TVs. Not only high-end devices, many low-cost Android smartphones are also equipped with OLED screens. However, not all OLED panels on these models are the same. Depending on the specific product, your device may use an OLED, AMOLED or POLED display. ## Features of OLED screen OLED screen has deep black color, bright color display, high contrast and brightness, wide viewing angle. OLED also has some drawbacks, the most common being image retention, but overall, this is a noticeable improvement over previous display technology. ## Infinite Contrast OLED screens have millions of carbon diodes, so the technology is called “organic Light-Emitting Diode (OLED). The diodes are a mixture of red, green and blue light emitting points, arranged in several ways. When an electric current flows through them, they emit light. Since each pixel independently processes its light and color, OLED displays don’t need their own backlight. The absence of a backlight helps OLED displays provide “infinite contrast”. Contrast is measured by comparing the brightest part of the screen with the darkest part. OLED screens can achieve a black level of 0 nit, so there is an infinite difference between the darkest and brightest points on the screen. Hence the contrast ratio is infinite. High contrast makes the content on the screen more vivid, the highlights look more impressive. This also allows OLED displays to achieve higher brightness than the best IPS LCD screens. ## Color and response rate OLED screens can display more colors and have higher color accuracy than LCDs of the same type. This feature enables photographers and videographers to use their phones to preview, edit and create content. OLEDs have near-instant pixel response times. LCD screens often require long response times because the physical orientation of the liquid crystal must be changed to change color. Meanwhile, OLED panels turn each pixel on or off with an electrical charge, making them more responsive. ## Transparent, thin and fragile The removal of the backlight and the use of fewer components make OLED screens thinner than LCD screens. This also means that they are more fragile, more susceptible to damage in situations of strong impact. Engineers overcome this using reinforced technology such as Gorilla Glass and metal frames. However, that also increases the cost of producing OLED screens. OLED screens can also be transparent, depending on the material used. Transparent screens are useful for in-display fingerprint readers and under-display cameras, allowing manufacturers to design smartphones with slimmer bezels and smaller bezels. ## Energy Saving Since OLED screens don’t need a backlight, blacks are produced by turning off the pixels, resulting in deep and consistent blacks. This feature allows manufacturers to implement features like an always-on display without sacrificing device battery life. However, OLED screens typically use more power at maximum brightness than LCD screens of comparable size. ## Image retention and degradation problems Like other technologies, OLED also has its downsides. OLED displays are susceptible to degradation over time and UV exposure, due to the organic nature of the molecules that make up the diodi. The physical construction of OLED displays also leads to image retention, where static user interface elements such as menus, navigation bars, and status bars leave a lasting ghosted image. Image retention is somewhat reduced thanks to the pixel shifting method and technological advances in recent years. ## Differences of OLED display types The original OLED display placed all organic materials on a glass substrate. However, glass is a hard material, requiring a more flexible substrate to create a foldable display. This problem led to the introduction of POLED displays. POLED (polymer organic light-emitting diode) has the advantage of durability and flexibility. Replacing glass substrates with polymers makes them more impact resistant. Designers can reduce bezel size by folding electronic components under one edge of the screen rather than on the same plane. POLED screens are also thinner than glass-based OLED screens. It is important to note the difference between POLED and pOLED. pOLED is the brand used by LG Display for its plastic OLED displays. They created this screen and applied it to many different products. pOLED appears on Google Pixel 2 XL, LG Velvet, and some smart wearables. However, it seems that LG’s pOLED screens have a higher risk of image retention. Google Pixel 2 XL users complain about image retention after only a few months of use. With the demand for high resolution screens on smartphones, manufacturers create AMOLED (active matrix organic light-emitting diode) displays. Older passive matrix OLED (PMOLED) displays require high voltage to achieve high resolution and pixels. The higher the voltage, the shorter the life of the display. Meanwhile, AMOLED uses a thin-film transistor array (TFT) to regulate the display’s electrical buildup. This makes OLED panels more energy efficient than PMOLED displays (which have non-tunable capacitors). Besides, AMOLED screen manufactured by Samsung, branded Super AMOLED, integrates an embedded touch layer. Dynamic AMOLED is used to refer to a display capable of displaying HDR. Many AMOLED screens also use plastic substrates, which carry the advantages of POLED screens such as increased durability and flexibility. ## Several factors affect display quality Screen technology is just one of many factors that affect display quality. They are useless without creating a different experience for the end user. Smartphone manufacturers use many methods to improve display quality, providing a better experience for customers. ## Resolution and pixel density Resolution is the number of pixels present on the screen, usually written as a ratio: pixels on the long edge times pixels on the short side, for example, 1920 x 1080. Most monitors Smartphones have resolutions between 720p (1280 x 720) on the low end and 4k (3480 x 2160) on some Sony models. 4k is far too high and rare for any device under 15 inches, but 720p, 1080p, and 1440p are all common smartphone resolutions. The ideal resolution for smartphone screens depends on the size. Another notable parameter is *pixels per inch* (PPI), which describes the number of pixels of the screen in vertical or horizontal inches. For a 6-inch screen, you should choose 1080p or higher than 350 PPI. ## Subpixel layout Subpixel layout is the arrangement of pixels on the screen to produce different colors. Subpixel is an element smaller than a pixel, covered with color filters, usually red (red), green (green) and blue (blue). RGB has been a popular layout for a long time. Some monitor manufacturers also use other layouts such as BGR, PenTile, RGBG, and WRGB. They can overcome various shortcomings of screen technology. As well as resolution, subpixel layout can affect image quality. Manufacturers and designers see RGB as a standard. They create optimized content for that layout. When manufacturers decide to create new subpixel layouts, quality suffers. Samsung uses PenTile screen, RGBG layout instead of RGB to overcome image retention on AMOLED screens. WRGB displays add a separate white subpixel to increase brightness. ## Refresh rate Refresh rate is the number of times the screen refreshes per second. High speed means smoother motion and animation. In general, 60 Hz is an acceptable refresh rate. Currently many high-end and mid-range Android smartphones have screens of 90 Hz, 120 Hz, 144 Hz, even 240 Hz. The 90 Hz or 120 Hz refresh rate also makes the screen more beautiful in normal use situations, but most users do not perceive it. Things only become more obvious when playing the game. However, a higher refresh rate will drain the battery. It is important to have a balanced choice. Technological advancements such as adaptive refresh rate, which allows devices to flexibly change the refresh rate in each situation, are the solution adopted by manufacturers. ## Brightness Smartphone is often used outdoors, so screen brightness is a very important factor. Screen brightness is measured in nits or cd/m². Peak brightness is the temporary maximum brightness of a part of the screen, while sustained brightness is a more realistic representation of the overall brightness of the screen. You should choose a monitor with a sustained brightness of over 600 nit. Lower levels can make it difficult to view or read content in brightly lit environments. On the other hand, luminance is measured in logarithms rather than linearly. That means 1,200 nits is only twice as bright as 300 nits. Users need to understand this. Many manufacturers rely on high luminance indicators as a marketing factor for their products.
