Flexible audible display using ITO on PVDF and its interface analysis

Abstract

Flexible audible display (FAD) based on PVDF(Poly-vinylidene fluoride) film is researched to combine piezoelectric property with light emitting diode. Indium-Tin-Oxide (ITO) is deposited on PVDF film at low temperature condition with the vacuum web coating. Under the optimized working pressure and the oxygen/argon pressure ratio, ITO on PVDF shows good electrical property of sheet resistance about 120 ohm/sq at 160 nm thickness, good transmittance of 76%, and sound pressure level more than 70 dB. OLED device with Al/LIF/Alq3/ NPB/ 2TNATA structure is fabricated on ITO/PVDF and shows the turn-on voltage of 3.5 V and the maximum luminescence of 1011.2 cd/㎠ at the driving voltage of 13 V. C-F chemical bondings are measured to decrease in the XPS spectrum of ITO/PVDF interface. This is originated from the bonding scission caused by incident energetic particles, such as sputtered atoms, backscattered Ar ions, and negative O ions during the sputtering and deposition process. These particles have energy, which is simulated by TRIM and is more than 5 eV, enough to cause the scission of C-F bondings with binding energy of 4 eV/atom.