Carboxylated graphene oxide as an efcient hole-injection layer in polymer light emitting diode

In this work, polymer light-emitting diode (PLED) with configuration of glass/ITO/GO-COOH/MEH-PPV/Al was fabricated. At first, indium tin oxide (ITO) thin film was deposited on glass substrates by radio frequency (RF) sputtering and the influence of synthetic carboxylated graphene oxide (GO-COOH) as the hole-injection layer (HIL) on the performance of the PLED made from poly [2-methoxy-5- (2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) was investigated. In addition, electrical and optical properties of ITO transparent electrode were measured. Finally, the device performance was investigated and compared with PLED fabricated with poly (3,4ethylenedioxythiophene): poly (p-styrenesulfonate) (PEDOT:PSS) as HIL. The Fowler-Nordheim (FN) tunneling model was used to estimate the hole injection barrier height (j) of the fabricated PLEDs. According to the obtained results, the GO-COOH layer improved the hole-injection within the PLED structure, resulting in the reduction of the turn-on voltage of the fabricated devices. As a result, it can be concluded that the GO-COOH can be used as a convenient HIL in PLEDs as well as other micro or nano electronic devices.