Effect of photoswitchable characteristics of spirooxazines on the electroluminescent property of polymer LEDs

Based on the photoswitchable characteristic of spirooxazines controlled by photochromic reactions, spiro[2H-indole-2,3'-[3H] phenanthr[9,10b] [1,4] oxazine(SO) as guest was doped to the active host MEH-PPV and the four layers architecture light-emitting diodes (LEDs) was fabricated using ITO as anode, PEDOT: PSS as hole-transport layer, MEH-PPV: SO as emitting layer, LiF and Al as cathode. The electroluminescent properties of LEDs was investigated by exposure to UV and visible light respectively. Through photochromic reaction, the ring-opening coloured of SO acted as traps for injected charge carries which influenced the behavior of LEDs. The electroluminescent characteristics of MEH-PPV diodes including current density, blighting and electroluminescent intensity may be changed through the reversible switchable charge traps of SO driven by light.