Ultraviolet-Enduring Performance of Flexible Pentacene TFTs with SnO2 Encapsulation Films

We report on the fabrication of flexible pentacene thin-film transistors (TFTs) encapsulated with an ultraviolet (UV)-protecting SnO 2 thin-film that has been prepared by ion-beam-assisted deposition (IBAD). We deposited thermally evaporated SnO 2 on a pentacene TFT as a buffer layer prior to the IBAD process. When a UV light of 254 nm wavelength was continuously illuminated onto our encapsulated device for periods of 5, 30, 60, and 120 min under a vacuum of 1 X 10 -6 Torr, its field mobility gradually degraded from 0.34 to 0.22 cm 2 /V s in 2 h while the other device without encapsulation rapidly degraded (its mobility was reduced to 0.021 cm 2 /V s during the same period). Our X-ray diffraction data indicates that the UV-induced-degradation of device characteristics is directly correlated to the degradation of pentacene crystallinity against UV radiation. We conclude that our IBAD SnO 2 encapsulation is a promising way to protect pentacene TFTs.

[1]  Thomas N. Jackson,et al.  Modeling of organic thin film transistors of different designs , 2000 .

[2]  Theo Siegrist,et al.  Photochemical Stability of Pentacene and a Substituted Pentacene in Solution and in Thin Films , 2004 .

[3]  S. Im,et al.  Pentacene-Based TTFTs with Polymer Gate Dielectric and NiO x Electrodes , 2005 .

[4]  Thomas N. Jackson,et al.  Pentacene organic thin-film transistors for circuit and display applications , 1999 .

[5]  Z. Popović,et al.  DEGRADATION PROCESSES AT THE CATHODE/ORGANIC INTERFACE IN ORGANIC LIGHT EMITTING DEVICES WITH MG:AG CATHODES , 1998 .

[6]  Thomas N. Jackson,et al.  Pentacene-based organic thin-film transistors , 1997 .

[7]  J. Rubim,et al.  Photo-degradation of synthetic and natural polyisoprenes at specific UV radiations , 2005 .

[8]  C. Tang,et al.  Application of an ultrathin LiF/Al bilayer in organic surface-emitting diodes , 2001 .

[9]  Michael A. Haase,et al.  Pentacene-based radio-frequency identification circuitry , 2003 .

[10]  Yasuhiko Arakawa,et al.  Organic light-emitting diodes driven by pentacene-based thin-film transistors , 2003 .

[11]  Zhenan Bao,et al.  Humidity effect on electrical performance of organic thin-film transistors , 2005 .

[12]  Torahiko Ando,et al.  Macromolecular electronic device: Field-effect transistor with a polythiophene thin film , 1986 .

[13]  Chang Su Kim,et al.  Encapsulation of Organic Field-Effect Transistors with Highly Polarizable Transparent Amorphous Oxide , 2005 .

[14]  Yong Qiu,et al.  H2O effect on the stability of organic thin-film field-effect transistors , 2003 .

[15]  H. Seggern,et al.  Sunlight stability of organic light-emitting diodes , 2005 .

[16]  Chang Su Kim,et al.  Enhancing the Ambient-Enduring Performance of Pentacene Thin-Film Transistors by SnO2-Encapsulation , 2005 .

[17]  C. D. Sheraw,et al.  Organic thin-film transistor-driven polymer-dispersed liquid crystal displays on flexible polymeric substrates , 2002 .

[18]  Jihoon Park,et al.  Flexible semitransparent pentacene thin-film transistors with polymer dielectric layers and NiOx electrodes , 2005 .