Flexible organic electroluminescent devices based on transparent clay films

We report the fabrication of flexible organic light-emitting diodes (OLEDs) using transparent clay films with heat-resistant and high-gas-barrier properties. Indium tin oxide (ITO) thin films were deposited as anode layers at high temperature using the rf magnetron sputtering method. The ITO films deposited at temperatures greater than 300 °C exhibit high optical transparency (>90%) in the visible region with a low electrical resistivity of 4 × 10 −4 Ω cm. Flexible OLEDs with the structure of clay film/ITO/TPD/Alq 3 /Al (where TPD is N , N ′ -diphenyl- N , N ′ -(3-methylphenyl)-[1,1 ′ - biphenyl]-4,4 ′ -diamine and Alq 3 is tris(8-hydroxyquinolinato) aluminum) showed a turn-on voltage of around 7.2 V, a luminance efficiency of 2.7 cd A −1 , and a luminance of 100 cd m −2 at 11.5 V. Results show that the clay film is an excellent candidate for transparent flexible substrates for use in displays or other electronic applications.