NTHU develops an efficient and long lasting bluelight-free tandem OLED device

Taiwan's National Tsing-Hua University (NTHU) Professor Jou and Dr. Wen have been developing OLED lighting technologies for many years, focusing on healthy bluelight-free OLEDs (so-called candle-light OLEDs) due to the hazards of modern lighting.

Light source spectrum comparison (NTHU, tandem OLED)

The researchers now report they have developed a new tandem-OLED device that improves the efficiency and lifetime of their candle-light OLEDs. The OLED's emission is totally blue-light free, which makes it even safer compared to NTHU's first-gen candle-light OLEDs.


The new OLED devices has a very low color temperature at 1,500 K - lower than that of actual candles (1,900 K). The researchers say it is 15 times more human eye-friendly and 30% more melatonin generation-friendly than a candle. The lifetime of the device is rated at 40,000 hours @ 1,000 cd/m2.

The researchers say that the device was made from commercially-available OLED materials (provided by Taiwan's Shine Materials Technology). Hopefully such device could find their way into the market. NTHU has already attempted to commercialize such technologies in the past - in 2015, NTHU developed its low blue-light candle-light orange-type OLED technology, initially in collaboration with Wisechip and later with China-based OLED lighting producer First-o-lite.

In 2019 we reported that NTHU has been promoting its candle-light OLEDs for the Smangus tribe in Taiwan's Jianshi Township which has been avoiding artificial light pollution till today. NTHU and the tribe managed to raise money to install 240 OLED lamps in street lights and residential lighting in the tribe's village.

Posted: Jul 25,2021 by Ron Mertens