Organic LEDs: DNA benefits

The nucleic acid bases that form DNA can serve as a useful hole-transport (electron blocking) layer in organic light emitting diodes (OLEDs), according to scientists in the USA. Eliot Gomez and co-workers report that because adenine and thymine can be thermally evaporated, they can be easily incorporated into the fabrication of OLEDs made by vacuum deposition and offer efficient hole-transport to the light emitting layer. Green phosphorescent OLEDs featuring adenine as a hole-transport layer achieved a peak current efficiency of 48 cd A–1 and a luminance of 93,000 cd m–2, and OLEDs using thymine achieved 76 cd A–1 and 132,000 cd m–2. In contrast, a reference device using the conventional holetransport material NPB yielded values of 37 cd A–1 and 113,000 cd m–2. The researchers believe the advantageous performance of the nucleic acid bases is due to their large highest occupied molecular orbital energy level, which helps create a more balanced electron– hole ratio within the device. The low cost and ease of fabrication and processing of natural charge transport layers could make them an attractive material choice in the future for use in optoelectronic devices. OG