pH-neutral PEDOT:PSS as hole injection layer in polymer light emitting diodes

✍ Scribed by Sha Wu; Shaohu Han; Yina Zheng; Hua Zheng; Nanliu Liu; Lei Wang; Yong Cao; Jian Wang

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 594 KB
• Volume: 12
• Category: Article
• ISSN: 1566-1199
• DOI: 10.1016/j.orgel.2010.12.015

✦ Synopsis

In the application of polymer light emitting diodes (PLEDs), to prevent etching of ITO by the acidic poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), the pHneutral PEDOT:PSS was introduced as the hole injection layer (HIL). For the double layer PEDOT:PSS HIL, the pH-neutral PEDOT:PSS on top of ITO stops the indium migration into the polymer, while the regular acidic PEDOT:PSS beneath the light emitting layer keeps the efficient hole injection. The performance of the double layer HIL PLEDs is comparable to or even better than that of the single layer HIL light emitting device. To use pH-neutral PEDOT:PSS as a single layer HIL, the neutral PEDOT:PSS layer was treated by UV and oxygen plasma. Such treatments reduced the hole injection barrier between the HIL and the light emission layer to improve the hole injection, leading to a device performance better than that of the regular acidic PEDOT:PSS HIL device.