TFT and AMOLED Technology. By Vidharshu Ray A2325312026

                                   TFT

Short for thin film transistor, a type of LCD flat-panel display screen, in which each pixel is controlled by from one to four transistors. The TFT technology provides the best resolution of all the flat-panel techniques, but it is also the most expensive. TFT screens are sometimes called active-matrix LCDs. A thin film transistor comprises :

a semiconductor layer

a gate insulating layer

a gate electrode

The semiconductor layer is typically a polysilicon layer whose electron mobility is 100 times higher than that of an amorphous silicon layer. Thin film transistors are used as switching devices in flat display panels such as organic light emitting diodes (OLEDs) or liquid crystal displays (LCDs).

• Types of TFT:-

           IPS - in-plane switching.

           MVA - multi-domain vertical alignment

           VA - patterned vertical alignment

           CPA - Continuous Pinwheel Alignment

• Advantages of using it:-

            1.Can be used as electrodes, or channel layers.

            2.High field effect mobility : 10 ~ 5

            3.Large area deposition.

            4.Rapid Process.

            5.Low cost.

            6.Low leakage current.

                                  

                                           AMOLED

It stands for Active Matrix OLED, is a hybrid display technology that pairs the active matrix backplane from a traditional TFT display with an OLED display. As a result of their active matrix natures, AMOLED displays have faster pixel switching response times than do traditional OLED displays, which are prone to ghosting when displaying fast moving animations.

• Advantages

Higher image resolution. Richer and more vibrant colors. AMOLED uses less voltage, and devices employing AMOLED technology have better battery life. AMOLED also manages to save battery by turning off pixels to display black pixels in an image. The displays are thinner and lighter than LCD or LED.

• Disadvantages

The current market for AMOLED devices is almost exclusively in handheld electronics due to the manufacturing difficulties associated with creating larger displays. For instance, making AMOLD available for larger flat screen televisions would require and overhaul in the manufacturing process of the back panels.

• How AMOLED works?

By employing an active matrix to control a system of OLED nodes, each being assigned an individual pixel in the display. The matrix is applied to a back panel, called a Thin Film Transistor, which regulates to flow of electrons to each individual pixel. The back panel is made of polycrystalline silicon and amorphous silicon. Two back panel layers will typically be employed; one acting as a voltage source and the other as a capacitor. The flow from layer to layer can be individually regulated, so for instance, a given pixel can shut itself off to render black.