Organic light sources look forward to optimize the photosynthesis process

We introduce a series of organic LEDs that exploit the monomer and excimer emissions from single phosphor dopant emitters. These organic LEDs were found to be effective in the simultaneous creation of blue and red emission bands essential for plant growth. By varying the concentration of novel phosphorescent dopants selected from a series of newly synthesized platinum complexes [PtL22-25CI], we have manufactured the blue-biased LEDs [with the Commission Internationale de L'Eclairage (CIE) coordinates (x,y) (0.27, 0.37)] and the red-biased LEDs [CIE coordinates (0.53, 0.38)], at a high luminance of approximate to 500 cd/m(2) and with external electroluminescence (EL) quantum efficiency of 15-18% photon/electron (-> power efficiency 8-12 lm/W). The EL spectrum most suitable for the action spectrum of photosynthesis yield was that of a device incorporating 20 wt.% content of [(PtLCI)-C-23]. This LED yielded photosynthetic photon flux (PPF) approaching 10 mu mol s(-1) W-1 of the electrical power, a value which significantly exceeds that for the professional lamps used commonly for horticultural lighting. (C) 2008 Elsevier B.V. All fights reserved.