Numerical analysis of instabilities of organic thin-film transistors for flexible displays

Calculating the threshold voltage shift with time (ΔV _th ) in organic thin-film transistors (OTFTs) is crucial for designing flexible display backplanes. The stretched-exponential time dependency of ΔV _th is widely accepted in various transistors to predict the shift. However, this analytical model is valid only when an OTFT is operated by constant voltages. In addition the model can't account for the recovery V _th because the model is formularized by integrating only charge trapping processes, which increases V _th . These shortcomings limit practical simulation which is required to design circuits. In order to calculate ΔV _th in a way that is more close to the real case, a numerical model is proposed based on the dynamics of charge trapping and detrapping. In simulation, multiple instances of the model are used to calculate both increase and decrease in V _th and the results shed light on the meaning of the parameters which are not obtainable from the analytical model.