Phosphorescent

During iMID 2024, Samsung Display's eVP Yi Chung said that the company plans to reduce the power consumption of its OLED panels by over 50%. SDC is developing several technologies, each contributing to the same efficiency goal.

SDC did not detail its plans exactly, but it did mention some of the new technologies it is working on - polarizer-free OLEDs (these have been commercialized already), multi-frequency driving (demonstrated by other OLED makers), tandem OLED architecture and the adoption of high efficiency blue PHOLED emitters.

A report from Korea says that LG Display has successfully developed an OLED panel that is based on a blue phosphorescence emitter. The blue PHOLED, provided by Universal Display, offers 100% IQE, up from 25% used by current fluorescence emitters. This will result in around 20-30% power saving for the display itself (depending on the images shown).

UDC has been developing blue emitters for many years, and recently the company said that the development will take a few more months and won't be ready in 2024. The main challenge is increasing the lifetime of the materials. However LG Display has adopted a tandem design to enable a commercially ready display, perhaps even sooner than UDC planned.

Samsung Display's Lee Chang-hee, VP and head of SDC's research center, gave a talk during K-Display 2024, and updated that Samsung is progressing towards a next-generation blue OLED emitter technology in two tracks.

SDC is working with Universal Display, to adopt the company's blue PHOLED system. This is progressing, but SDC says that the pace is slow - indeed we heard from UDC lately that the introduction of a commercial material will take longer than expected.

OLED displays have been gaining popularity rapidly, and are already the dominant smartphone display technology. OLEDs are also the display technology of choice in the smartwatch market, making inroads into the TV, monitor, laptop and tablet markets. The future of the OLED industry looks bright.

In recent years, the focus of the industry, beyond increasing capacity and reducing production costs, has been improving the performance of OLEDs in the areas of display brightness, efficiency, and lifetime. Brightness is required in many applications - from TVs (for HDR and to view in ambient lighting) through smartphones (outdoor viewing) to automotive, and efficiency is a plus in any scenario (but mostly in mobile displays). Display lifetime is already good enough for many applications, but in some cases (like automotive, and IT displays) it is critical. These three properties usually go together - if you can make more efficient OLED displays, you can drive them at a lower current to achieve the same brightness, and so lifetime increases, or you can achieve higher brightness, etc. 

Researchers from Osaka University have found that thienyl diketone, a new organic molecule, shows high-efficiency phosphorescence, and one that is more than ten times faster than traditional organic phosphorescence materials. Such a material could hold promise for highly-efficient phosphorescence emission without the use of heavy metals. 

The researchers explain that phosphorescence occurs when a molecule transitions from a high-energy state to a low-energy state, and it often competes with non-radiative processes (i.e. heat generation instead of light). This competition with the non-radiative process leads to slow phosphorescence and lower efficiency. This is solved by adding heavy metal into the emitter - but this new breakthrough achieves fast emission without the heavy metal.

Universal Display Corporation reported its financial results for Q4 2023, with revenues of $158 million, and a net income of $62 million. For the whole year (2023), UDC reproted revenues of $576 million and net income of $203 million. The company ended 2023 with $800 million in cash and equivalents, and has increased its quarterly dividend.

UDC says that the market still suffers from soft spending in smartphone and premium TVs. UDC, however, says that it believes that the OLED industry is starting a new and exciting multiyear investment cycle.

DSCC estimates that the market for OLED evaporation materials (i.e. OLED stack materials) will reach $1.7 billion in 2023, and will grow to $2.7 billion in 2027 (a 11% CAGR from 2023). If UDC will succeed to commercially introduce a blue phosphorescence material, revenues can even be much higher.

OLED materials used in TV applications (and other large-area applications) will grow from $305 million in 2023, to $492 million in 2027, a 13% CAGR. DSCC also sees very fast growth in material used to produce tandem-structure IT displays, which will grow at a 79% CAGR to reach $443 million in 2027.

Researchers from the University of Michigan developed a new OLED emitter system, based on a blue phosphorescence emitter, based on the polariton-enhanced Purcell effect. This new emitter systems offers high stability and high efficiency. 

The basic idea is to start with a light-blue (cyan) phosphorescence emitter (which offers a longer lifetime than a deep blue emitter), and placing it between two mirrors. The distance between the mirrors is controlled so that only deep blue light waves persist and are emitter from the mirror chamber. The researchers also tuned the optical properties of the OLED stack to the adjacent metal electrode which introduced a new quantum mechanical state called a plasmon-exciton-polariton, or PEP. This new state allows the organic material to emit light very fast, thus even further increasing the lifetime by decreasing the opportunity for excited states to collide and destroy the light-emitting material.