" In a p-n junction diode not connected to any circuit "

If a p-n junction diode is not connected in a circuit then

P-N junction diodes

p-n junction diode acts as

a p-n junction diode cannot be used

What is a p-n junction diode?

p-n junction diode can be used as

p -type crystal of a p-n junction diode is connected to a positive terminal of battery and n -type crystal connected to negative terminal of battery