Question

The I-V characteristics graph shown below is exhibited by

• A. LED
• B. Zener diode
• C. Photodiode
• D. Solar cell

Hint:

Remember the operation quadrants of optoelectronic devices:
- First Quadrant: Light Emitting Diode (LED)
- Third Quadrant: Photodiode (reverse-bias operation)
- Fourth Quadrant: Solar Cell (power-generating device)
This is a standard classification that helps you identify the device immediately.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Different semiconductor devices have unique Current-Voltage (I-V) characteristic curves that define their operating behavior.
- LED: Operates in forward bias; current increases exponentially after a threshold voltage.
- Zener Diode: Designed to operate in the reverse breakdown region; constant voltage for varying current.
- Photodiode: Operates in reverse bias; the curve shifts downwards with increasing light intensity.
- Solar Cell: Operates as a power source. Its I-V curve is usually drawn in the fourth quadrant (or inverted) to show it delivering power rather than consuming it.
Step 2: Key Formula or Approach:
Examine the intercepts on the axes.
The x-intercept is the Open Circuit Voltage (\(V_{oc}\)).
The y-intercept is the Short Circuit Current (\(I_{sc}\)).
Step 3: Detailed Explanation:
The provided graph shows the curve in the region where \(V>0\) and \(I<0\).
This indicates that the device is generating a potential difference while a current flows out of it (opposite to the direction of an applied bias).
When the voltage is zero, there is a maximum current called the short-circuit current.
When the current is zero, there is a maximum voltage called the open-circuit voltage.
This is the classic operating curve for a solar cell. It operates in the fourth quadrant because it is a source of electrical energy (power generator).
Photodiodes also show behavior in this region, but their characteristic plots usually emphasize the third quadrant (reverse bias) with varying light intensities. A single curve passing through \(V_{oc}\) and \(I_{sc}\) as shown is specifically the standard representation of a solar cell.
Step 4: Final Answer:
The characteristic curve passing through the fourth quadrant with defined open-circuit voltage and short-circuit current is the signature of a solar cell.