Efficient very-high color rendering index organic light-emitting diode

Very-high color rendering index (CRI > 90) is extremely crucial for lighting in surgery, photography and exhibition of museums etc. We demonstrate herein an efficient very-high CRI organic light-emitting diode with CRI of 98 with an efficacy of 8.3 lm/W at 100 cd/m2, or CRI of 96 with 5.2 lm/W at 1000 cd/m2. The very high CRI may be attributed to the successful deposition and emission of the two full-spectrum complementary white emissive layers, especially as a thin interlayer is inserted in between to regulate the injection of carriers. Without the interlayer, the resultant CRI drops to 73 and efficacy to 3.6 lm/W at 1000 cd/m2. The employment of the carrier regulating layer also helps disperse the injected carriers, leading recombination to occur in a wider area and hence a higher efficiency.