Electroluminescence as a probe for electrical and optical properties of deoxyribonucleic acid

摘要

Several class of dyes doped in deoxyribonucleic acid (DNA) derived from salmon show enhancement of fluorescence due to suppression of molecular aggregation. Also, some recent studies support electric conduction in DNA strands. Combination of these properties suggests the possibility to develop organic LED devices (OLED) based on biopolymer systems. Furthermore, the electroluminescence (EL) effect can be employed as a probe for electrical and optical properties of DNA. We fabricated OLED devices based on DNA-lipid complex and dopant dyes (ethidium bromide and fluorescein). Devices are composed of hole injection layer, dye-doped DNA-lipid layer and electrodes. OLED with ethidium bromide doped DNA showed LED emission under DC bias, but the origin of the mission was tris-(8-hydroxyquinolinato) aluminum (III) (Alq3) which was employed as an electron transporter. The current-voltage characteristics of the devices show apparent rectification behavior. From these experimental results, it is confirmed that DNA transports hole current under external DC bias. When employing fluorescein as a dopant in DNA and fabricating the devices without Alq3 layer, we observed emission from the dyes incorporated in DNA. Although the origins of the emission centers in spectra are not clear, it shows that the DNA-lipid complex will be basically applicable to OLED if additional improvements are made.