Indium blocking in polymer light emitting diodes with a crosslinked poly(3,4-ethylenedioxythiophene)/silane hole transport layer

A novel crosslinkable hole transport material, a mixed compound of poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate) (PEDOT)/glycidoxypropyl trimethoxysilane (GPS), has been developed to protect indium contamination from indium tin oxide (ITO) substrates. The curing behavior of the PEDOT/GPS was monitored with Raman spectroscopy and indium contamination was observed with X-ray photoelectron spectroscopy. The hole transport material immediately formed a crosslinked siloxane network structure after spin casting and reduced the indium incorporation in the hole transport layer. The addition of GPS was effective in protecting the indium contamination from ITO substrates through a crosslinked network formation.