Which LCD technology is best for sunlight readability?
LCD’s with a reflective polarizer are the best for sunlight readability. Reflective means that 100% of the sunlight is reflected to the user, making the characters/icons sharp and easy to read.
The original Amazon Kindle® used a reflective polarizer and no backlight.
Reflective polarizers are available in: Character, Segment and Monochrome Graphic displays.
Multi-color displays, such as TFT and OLED use a transmissive polarizer that is difficult to read in direct sunlight. To allow these displays to be readable in high light environments, their backlight brightness is increased up to 750 nits or greater. (one Nit is the amount of light produced by one candle.) The increased brightness drains more power and are not always best for battery powered products.
Here is a quick article to introduce the three different polarizers and which is best for your new design.