OLED in sunlight

US-based Light Polymers launched a new circular polarizer for OLED displays based on its lyotropic liquid crystal technology. The new polarizer is said to be the world's thinner polarizer at only 45 µm.

These lyotropic liquid crystals are water-based, and can be coated using industry standard coating equipment at nearly room temperatures. This enables the company to produce these displays at a lower-cost compared to alternatives, and its production line can currently coat around 30-40 million m² per year, costing a tenth of the capex and lower energy costs than competing processes (this is according to Light Polymers, of course).

In April 2016, Japan's Semiconductor Energy Laboratory (SEL) and Advanced Film Device announced they have developed a hybrid OLED - reflective LCD display, that can switch between an OLED mode (for dark environments) and reflective LCD mode (for sunlight visibility). Such a display could be very power efficient.

TR-Hybrid in OLED mode

SEL demonstrated a prototype display at SID 2016, and provided more information. SEL calls these displays TR-Hybrid displays (TR means Transmissive OLED and Reflective LC). To create this display, SEL introduced holes into the reflecting electrodes of a reflective LCD, and the OLED layer beneath transmitted light through these holes in OLED mode.

Researchers from Japan's Semiconductor Energy Laboratory (SEL) and Advanced Film Device developed a display that includes an OLED display on top of a reflective LCD. The idea is that such a display have high visibility in both a dark environment (using the emissive OLED) and a bright one (using the reflective LCD).

This is similar somewhat to transflective LCD displays and can prove to be a smart solution. The researchers say that the same FET layer is used to control both display devices and so results in a low-power device. The researchers will present this new development at SID DisplayWeek next month and hopefully we will bring more information.

US-based Light Polymers announced a new coating material that improves the contrast and readability of OLED displays in bright sunlight. The material is based on the company's lyotropic liquid crystals, and can be coated on substrates such as TAC, acrylic and initially COP. The company also plans to enable reverse dispersion coatings directly on the OLED panel glass.

OLED behave quite poorly in bright ambient light - due to the reflective metal transistors. There are some solutions of course (Samsung's Super AMOLED and Nokia's Clear Black Display technologies are two examples) - and Light Polymers says that their solution is lower-cost, and can be coated directly on the OLED panel - something that cannot be done with other technologies.

IHS estimates the current OLED lighting market (at the panel level) at $2.7 million in 2014, and says that the market will grow tenfold by 2020 - to reach $26 million. IHS expects panel prices to drop 40% in the next several years, but OLEDs will still not be able to compete with LED lighting, and this is why it does not expect OLED lighting to really emerge as a mass market in the near future.

A Philips OLED installation

IHS is rather pessimistic, and other analysts see panel prices dropping much more quickly and volumes rise at a much more dramatic rate. IDTechEx for example see a $200 million panel market in 2019 that will grow to $1.9 billion in 2025. Cintelliq sees OLED competing with LEDs in 2016, and 500 million 100x100 mm OLED lighting panels produced in 2023.

Raymond Soneira, our friend and display guru from DisplayMate have posted a very interesting and detailed comparison of the OLED displays in the Galaxy S, SII and SIII phones. He says that while all three OLED panels performed very well, there has been a rapid and significant improvement in OLED performance (especially power efficiency) in just 2 years.

Raymond says that high-end LCDs are brighter and more power efficient than OLEDs for text and web applications. OLEDs are better for photos and videos. He also says that while the performance is excellent, it's been compromised by Samsung's implementation choices - especially the low brightness due to power constraints (although low reflectence on those devices mean that high brightness is not critical in most situations).

DisplayMate performed some testing of several smartphones and tablets under bright ambient lighting. The handset that came on top was Nokia's Lumia 900 (which uses the company' ClearBlack Display technology and an AMOLED display). The second-best handsets are the iPhone 4 and the Super-AMOLED packing Samsung Galaxy S.

Nokia's ClearBlack Display technology has been announced in September 2010, and Nokia is using it in several phones (including the Lumia 900, Lumia 800 and older Symbian models such as the X7 and E7). We know that it includes polarizing filters to block incoming light. Today however Nokia finally revealed how it actually works:

A CBD filter includes both a linear polariser and retardation layers between the surface of your phone and the display. When light hits your screen, this is what happens:

Nokia's ClearBlack Display technology has been announced in September 2010, but only now did they explained this technology fully. We knew that CBD adds a polarizing filter to a display (which can be either an LCD or an OLED) - but Nokia now tells us that the filter is placed between the touch layer and the actual display - which enables it to block incoming light and not harm the contrast or color quality. In the photo below, we can see a normal C6-01 phone with a CBD display (on the left) and the same phone without the CBD layer (on the right):

While the technology behind CBD displays is quite different to the one used in Samsung's Super AMOLED displays (which uses an on-cell touch layer) - the resulting image quality and behavior under sunlight is pretty similar in both display technologies.

LG announced a new mobile phone, the Optimus Sol - and this is the first phone that uses LG Display's new AMOLED displays (at 3.8"). LG brands these Ultra-AMOLED, and they say that they use new technology that makes them better under sunlight (and also offer better colors and reduced image degradation). We guess that (like Samsung's Super-AMOLED) these display include the touch-sensor in the display panel itself. Or perhaps they include a polarizing filter like Nokia's ClearBlack displays. The phone also includes a new "Dark UI" which conserves power on the AMOLED display - around 20%-30% according to LG.

LG Display are currently making 4,000 monthly substrate in their new 4.5-Gen AMOLED plant (which is about 500,000 3" displays). The company announced they will not invest further in small AMOLED production and will focus on large panels for OLED TVs.