OLED or Organic Light Emitting Diode technology is a relatively new technology in the field of displays. It has advantages in terms of power consumption, picture quality, and slimness compared to the traditional CRT or Cathode Ray Tube and TFT or Thin-Film Transistor displays. Here, we will analyze the principle of OLED technology from the perspective of physics and light emission and compare it with the principles of CRT and TFT.

 

CRT technology works on the principle of electron beams emitted by a cathode and directed towards a phosphor coated screen on the front side. The electron beam excites the phosphor, and it emits light of various colors depending on the chemistry of the phosphor material. The color and intensity of the light depend on the electron energy and the coating on the phosphor. The electrons are directed towards a specific point on the screen by a magnetic deflection field generated by a set of coils. CRT displays were widely used in the past and are still used, but their usage is becoming limited due to the advent of newer technologies.

 

TFT, on the other hand, is a technology that works on the principle of a transistor's electronic switching action. Each pixel in TFT is controlled by a thin-film transistor that connects to a capacitor holding a charge that maintains the pixel color. The transistor's switching action determines when the charge is allowed to pass through to the pixel and when it is not. This principle of switching the light on and off is the basis for TFT display technology.

 

OLED technology is based on the principle of organic materials that emit light when subjected to an electrical current. OLED pixels are made up of thin layers of organic materials, between two electrodes, namely an anode and a cathode. When an electrical current is passed through the organic layer, it emits light. The organic materials used in OLED are composed of carbon and hydrogen, which are arranged in a way that allows them to convert electrical energy to light efficiently. The brightness and color of the light depend on the organic material's composition and the voltage applied across it.

 

In terms of principle, OLED technology is more similar to the CRT than the TFT. OLED and CRT share the principle of light emission by specific materials that are directly excited by electrons or electrical current. The organic layer in an OLED emits light in response to electrical current passing through it. The phosphor layer in a CRT emits light when excited by electrons. The TFT, on the other hand, works on the principle of electronic switching, which is quite different from CRT and OLED.

 

Furthermore, OLED and CRT displays share the same advantages when compared to TFT displays. OLED and CRT have much better color reproduction, contrast, and viewing angles than TFT displays. OLED technology has taken advantage of the advances in materials science to create some of the most vibrant and efficient displays currently available.

 

In conclusion, OLED technology is more similar to CRT in principle than TFT. OLED technology utilizes the principle of light emission from an organic layer, which is directly excited by an electrical current in a way that is similar to the principle of light emission in a CRT. OLED shares the same advantages in terms of color reproduction, contrast, and viewing angles with CRT, further highlighting the similarity of the two technologies.