An AMOLED Pixel Circuit Based on LTPS Thin-film Transistors with Mono-Type Scanning Driving

Abstract

Using low-temperature poly-silicon thin-film transistors (LTPS TFTs) as a basis, a pixel circuit for an active matrix organic light-emitting diode (AMOLED) with narrow bezel displays was developed. The pixel circuit features mono-type scanning signals, elimination of static power lines, and pixel-integrated emitting control functions. Therefore, gate driver circuits of the display bezel can be simplified efficiently. In addition, the pixel circuit has a high-resolution design due to an increase of the pulse width of the scan signal to extend the threshold voltage and internal–resistance drop (IR drop) detection period. Further, regarding the influences of process–voltage–temperature (PVT) variation in the pixel circuit, comparison investigations were carried out with the proposed circuit and other pixel circuits with mono-type scanning signals using Monte Carlo analysis. The feasibility of the proposed pixel circuit is well demonstrated, as the current variations can be reduced to 2.1% for the supplied power reduced from 5 V to 3 V due to IR drop, and the current variation is as low as 10.6% with operating temperatures from –40 degrees to 85 degrees.

A Pixel Circuit for Compensating Electrical Characteristics Variation and OLED Degradation

“…As shown in Figure 2a, the circuit consists of one driving TFT (T2), four switching TFTs (T1, T3, T4, T5), and two capacitors (C1, C2). Therefore, lots of valuable voltage compensation pixel circuits have been reported [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. In [17][18][19][20][21], the circuits can compensate the threshold voltage variation successfully.…”

“…Therefore, lots of valuable voltage compensation pixel circuits have been reported [17][18][19][20][21][22][23][24][25][26][27][28][29][30].…”

“…In [17][18][19][20][21], the circuits can compensate the threshold voltage variation successfully. In [22][23][24][25], the circuits can compensate both threshold voltage and mobility variations successfully.…”

A Simple Scan Driver Circuit Suitable for Depletion-Mode Metal-Oxide Thin-Film Transistors in Active-Matrix Displays

“…A LTPS TFT has the advantages of high reliability and a small circuit area owing to its high carrier mobility. However, the excimer laser process of a LTPS TFT is a critical obstacle to reducing the manufacturing cost [2,3] so it has been primarily used in small-area mobile displays [6][7][8].…”

Bandgap Engineering of an Aryl-Fused Tetrathianaphthalene for Visible-Blind Organic Field-Effect Transistors

“…The high photoabsorption coefficients of OSCs are favorable for application such as organic photovoltaics (OPVs), but lead to serious stability problems in OFETs because both mobilities and threshold voltages of OFETs change after photoabsorption by the photoconduction and/or photogating effects (Baeg, et al, 2013;Min, et al, 2019Min, et al, , 2021. For applications such as thin film transistor (TFT) drive of AMOLED, variations in mobility and/or threshold voltage hinder the fabrication of large AMOLED displays with high uniformity (Ke et al, 2020). What's worse, material degradation may occur after photoabsorption (Forrest Stephen, 2015).…”