UPSC Prelims 2017 Q74: Science & Technology – Computer & Information Technology
Organic Light Emitting Diodes (OLEDs) are used to create digital display in many devices.
What are the advantages of OLED displays over Liquid Crystal displays?
1. OLED displays can be fabricated on flexible plastic substrates.
2. Roll - up displays embedded in clothing can be made using OLEDs.
3. Transparent displays are possible using OLEDs.
Select the correct answer
using the code given below:
- (a) 1 and 3 only
- (b) 2 only
- (c) 1, 2 and 3
- (d) None of the above statements is correct
Answer: (c) 1, 2 and 3
Explanation
OLED displays versus Liquid Crystal displays
An Organic Light Emitting Diode makes its own light.
A Liquid Crystal display needs a backlight.
So OLED panels can be very thin.
| Statement | Verdict | Fact |
|---|---|---|
| 1. OLED displays can be fabricated on flexible plastic substrates | Correct | The organic layers can be laid on plastic instead of glass |
| 2. Roll-up displays embedded in clothing can be made using OLEDs | Correct | Flexible OLEDs can be rolled and built into fabric |
| 3. Transparent displays are possible using OLEDs | Correct | With no backlight, the panel can be made see-through |
OLED and LCD compared:
| Feature | OLED | LCD |
|---|---|---|
| Light source | Each pixel emits light | Backlight needed |
| Black level | True black (pixel off) | Greyish |
| Flexibility | Flexible | Rigid |
| Weak point | Shorter life of organic material | Thicker panel |
Answer: (c) 1, 2 and 3.
Why each option is right or wrong
- (a) Incorrect. Statement 2 is also true: roll-up displays in clothing are possible.
- (b) Incorrect. Statements 1 and 3 are also true: flexible and transparent displays.
- (c) CORRECT. OLEDs allow flexible, roll-up and transparent displays.
- (d) Incorrect. All three statements are correct advantages of OLED displays.
Key point
OLED: self-emitting pixels, no backlight; allows thin, flexible, roll-up and transparent displays; LCD needs a backlight.
Remember
OLED = no backlight = flexible + transparent.
Common mistakes
- Thinking a roll-up display in clothing is too far-fetched to be right.
- Confusing OLED with LED-backlit LCD screens.
- Forgetting that OLED needs no backlight, which is why it can be transparent.
Exam tip
No backlight explains everything: thin, bendable and see-through.
Sources
- NCERT Class XII — Physics Part II (Semiconductor Electronics: Light Emitting Diode)
- US Department of Energy — OLED Basics