Abstract

Hydrogenated amorphous silicon (a-Si:H) active matrix organic light-emitting diode (AMOLED) displays are attractive given the potentially low manufacturing cost and ultimately low-temperature fabrication enabling using flexible substrates. Although the conventional two thin-film transistor (2-TFT) AMOLED voltage-programmed pixel circuit (VPPC) can provide high resolution and high yield, the 2-TFT VPPC is prone to image retention over time due to shift in the threshold voltage (V<sub>T</sub>-shift) of a-Si:H TFTs. This paper presents a new driving scheme that not only preserves the simplicity of the 2-TFT VPPC, but also demonstrates high uniformity. Experimental results indicate that the current drop in the new driving scheme is less than 11% after 15 days of operation whereas it is over 50% for the conventional driving scheme. Moreover, the new driving scheme is less sensitive to temperature variations due to an internal feedback mechanism. After a 70% change in the temperature, the current in the conventional driving scheme increases by as much as 300%. However, the current in the driving scheme presented here is approximately constant.

© 2006 IEEE

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  2. A. Nathan, G. R. Chaji, S. J. Ashtiani, "Driving schemes for a-Si and LTPS AMOLED displays," J. Display Technol. 1, 267-277 (2005).
  3. G. R. Chaji, P. Servati, A. Nathan, "Driving scheme for the stable operation of the 2-TFT a-Si AMOLED pixel," Electron. Lett. 8, 499-500 (2005).
  4. P. Servati, A. Nathan, "Modeling of the static and dynamic behavior of hydrogenated amorphous silicon thin-film transistors," J. Vac. Sci. Tech. 20, 1038-1042 (2002).
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  12. J. H. Jung, "A 14.1 inch full color AMOLED display with top emission structure and a-Si TFT backplane," Tech. Dig. SID Symp. (2005) pp. 1538-1541.

Appl. Phys. Lett. (1)

M. J. Powell, C. Berkel, J. R. Hughes, "Time and temperature dependence of instability mechanisms in amorphous silicon thin-film transistors," Appl. Phys. Lett. 54, 1323-1325 (1989).

Appl. Phys. Lett. (2)

S. M. Jahinuzzaman, A. Sultana, K. Sakariya, P. Servati, A. Nathan, "Threshold voltage instability of amorphous silicon thin-film transistors under constant current stress," Appl. Phys. Lett. 87, 023502-1-023502-3 (2005).

M. J. Powell, S. C. Deane, W. I. Milne, "Bias-stress-induced creation and removal of dangling-bond states in amorphous silicon thin-film transistors," Appl. Phys. Lett. 60, 207-209 (1992).

Electron. Lett. (1)

G. R. Chaji, P. Servati, A. Nathan, "Driving scheme for the stable operation of the 2-TFT a-Si AMOLED pixel," Electron. Lett. 8, 499-500 (2005).

IEEE Electron Device Lett. (1)

J. H. Lee, J. H. Kim, M. K. Han, "A new a-Si:H TFT pixel circuit compensating the threshold voltage shift of a-Si:H TFT and OLED for active matrix OLED," IEEE Electron Device Lett. 26, 897-899 (2005).

IEEE J. Solid-State Circuits (2)

B. J. Sheu, C. Hu, "Switch-induced error voltage on a switched capacitor," IEEE J. Solid-State Circuits SC-19, 519-525 (1984).

G. Wegmann, E. A. Vitoz, F. Rahali, "Charge injection in analog MOS switches," IEEE J. Solid-State Circuits SC-22, 1091-1097 (1987).

J. Display Technol. (1)

J. Soc. Inf. Display (1)

M. Hack, J. J. Brown, J. K. Mahon, R. C. Kwong, R. Hewitt, "Performance of high-efficiency AMOLED displays," J. Soc. Inf. Display 9, 191-195 (2001).

J. Vac. Sci. Tech. (1)

P. Servati, A. Nathan, "Modeling of the static and dynamic behavior of hydrogenated amorphous silicon thin-film transistors," J. Vac. Sci. Tech. 20, 1038-1042 (2002).

Science (1)

H. Aziz, Z. D. Popovic, N. X. Hu, A. M. Hor, G. Xu, "Degradation mechanism of small molecule-based organic light-emitting devices," Science 283, 1900-1902 (1999).

Other (1)

J. H. Jung, "A 14.1 inch full color AMOLED display with top emission structure and a-Si TFT backplane," Tech. Dig. SID Symp. (2005) pp. 1538-1541.

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