Light emission at 5V from a polymer device with a millimeter-sized interelectrode gap

Abstract

We report the onset of electrochemicaldoping and subsequent visible light emission at 5 V and 360 K from a planar light-emitting electrochemical cell with a 1 mm interelectrode gap containing poly[2-methoxy-5-( 2 ′ -ethyl-hexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), poly(ethylene oxide) (PEO), and X C F 3 S O 3 ( X = K , Li ) as the active material. We rationalize the unprecedented low turn-on voltage of such wide-gap light-emitting electrochemical cells by demonstrating that the active material contains a mixture of crystalline PEO + X C F 3 S O 3 domains and amorphous MEH-PPV domains at room temperature, but that the crystalline domains have melted at 360 K resulting in a significant increase in the ionic conductivity.