We discuss the design of bilayer organic light emitting diodes (OLEDs) formed using adenine sandwiched between indium tin oxide (ITO) and Al, which were fabricated into four types of device structure. The electroluminescence intensities were characterized as a function of the current and voltage. The efficiency was significantly greater in bilayer devices in which adenine were used. The performance of green light emission with adenine-based devices was significantly greater than that reported to date (we find a luminance of -4227cd/m2 at a voltage of -8 V). The multi-layer OLED devices were formed of ITO, N,N__ampersandsignrsquo;-bis(naphthalen- 1-yl)-N,N?-bis(phenyl)benzidine (NPB), adenine, Tris(8-hydroxyquinolinato)aluminium (Alq3) and aluminium (Al). We find that the thickness of the adenine light-emitting layer determined the brightness and efficiency, as well as the operating voltage. The thickness of the adenine layer was optimized to improve the efficiency of the OLEDs.