Transparent thermally stable poly(etherimide) film as flexible substrate for OLEDs

In this work, ITO thin films were deposited onto poly(etherimide) (PEI) substrates at room temperature using r.f. magnetron sputtering and successively they were annealed in the 423–523 K (150–250 °C) temperature range. PEI/ITO substrates were structurally, optically and electrically characterized in order to verify the quality of the deposited ITO films and the PEI thermal stability during the ITO annealing process. A transmittance of about 80% was measured in the visible range. The best electrical properties achieved were: 3.04 × 10− 4 Ω cm, 12.07 × 1021cm2/V.s, 16.8 × 1021 cm− 3, for resistivity, carrier concentration and mobility, respectively. Small molecule Flexible Organic Light Emitting Diodes (FOLED) were then fabricated and characterized onto ITO functionalized PEI substrates. These preliminary results show clearly that PEI can be successfully used as substrate in flexible optoelectronic devices either operating in high temperature or when the process needs high temperatures.