OLED Displays use organic light-emitting diodes to display pixels. Since each pixel is its own light source, these displays have an excellent contrast, can be clearly read from a wide viewing angle and are readable in dim as well as very bright environments.
They come in different sizes and resolutions: common sizes are 0.48, 0.91, 0.96, 1.3, and 1.5 inch.
Resolutions start at 96x32, and (in economic price ranges) end at 128x128 pixels.
Overview
OLED displays are expensive to produce which is why affordable OLED displays for DIY projects are very small and typically single-colored.
Surprisingly, these limitations make OLED displays very attractive for certain use cases: since the amount of data that needs to be transferred from a microcontroller to the display is small, a simple two-wire I2C interface is sufficient to connect these displays to a microcontroller, saving precious GPIOs.
While you certainly wouldn’t use these small OLED displays for watching videos, they are perfect for displaying sensor information, provide device feedback, indicate charging status, and alike. And since OLED does not require backlighting, they do not require as much energy as other types of display. That’s a big advantage in battery-driven use cases.
Since in OLED displays, each pixel is an independent light source, the power consumption largely depends on how many pixels are on. That’s why white content on back background is much more efficient for OLED displays than black text on white background. With mixed content, OLED displays typically consume 40-60% of the energy a comparable LCD display would require.
Caveats
There are two specific caveats with OLED displays:
- Limited Life-Span: their organic materials can degrade over time which leads to decreasing brightness. However, this effect may become visible only after more than 10.000 hours of operation. It may be a problem in TV sets that are turned on continuously day and night. It is not a typical problem in DIY projects.
- Burn In/Ghosting: *OLED displays are susceptible to image retention (burn in aka ghosting) if static images are displayed for extended periods. This may be a problem in DIY projects as most device display designs do use a rather static layout.
Both shortcomings can be overcome though by turning OLED displays off when they are not needed, much similar to how many OLED-based smartwatches and smartphones work. This strategy also helps conserving power. Here is the typical behavior of such devices:
When there is information to display, the firmware turns the display on. After a certain time period, the display automatically turns off (or dims). Typically, users can press a key on the device to turn the display on anytime when needed.
OLED Driver Chips
OLED displays require a driver chip that takes the information to be displayed and draws it to the screen. Knowing the driver chip used on a particular OLED breakout board is important because the chip type determines which software library your code needs in order to work with the display.
These are commonly found OLED drivers in breakout boards:
- Small Monochrome - SSD1306: Entry-level for small monochrome (1bit) displays up to a resolution of 128x64 pixels. Uses I2C.
- Small Monochrome - SH1106: Very similar to SSD1306, resolution of 132x64 pixels. No hardware scroll functions. Uses I2C.
- Large Monochrome - SH1107: Supports monochrome (1bit) resolutions of up to 128x128. Supports I2C and SPI.
- Large Grayscale - SSD1327: Supports 16 levels of gray (4bit) and resolutions of up to 128x128 pixels. Supports I2C and SPI.
- Small Color - SSD1331: Supports 65k color (16bit) and resolutions of up to 96x64 pixels. Supports I2C and SPI.
- Large Color - SSD1351: Supports 262k color (18bit) and resolutions of up to 128x128 pixels. This driver supports SPI only.
There are many more OLED drivers. The software library u8g2 aims to provide a hardware-independent solution for a multitide of OLED drivers. It lists many more OLED drivers and their specifications.
Data Sheets
SSD1306
SSD1327
SSD1331
SSD1351
SH1106
SH1107
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(content created May 05, 2024)