An electron-hole supercapacitor

[Moreno]

What do you think about hypothetical supercapacitor in which charge would be stored in electron-hole double layer created between a conductor (which could be graphene or activated carbon) and a hole conductor (which could be a P-type semiconductor)? Difference in work function suppose to prevent electrons migrate inside a P-type semiconductor and recombine with the holes. A hole conductor could serve as a separator between electrodes. Were there such ideas in the past? What farther could prevent recombination? Do you think such capacitor going to leak charge?

Edited January 16, 2019 by Moreno

[Strange]

13 hours ago, Moreno said:

A hole conductor could serve as a separator between electrodes.

How can you use a conductor as the dielectric?

The nearest thing I can think of is using a (reverse-biased) diode as a capacitor: https://en.wikipedia.org/wiki/Varicap

[Moreno]

2 hours ago, Strange said:

How can you use a conductor as the dielectric?

The nearest thing I can think of is using a (reverse-biased) diode as a capacitor: https://en.wikipedia.org/wiki/Varicap

1) In suppose to conduct holes but no electrons. So, when electrons are transferred from one electrode to another one, it doesn't permit them to return back.

2) It does have quite a different structure from what I described.

[Strange]

13 minutes ago, Moreno said:

1) In suppose to conduct holes but no electrons. So, when electrons are transferred from one electrode to another one, it doesn't permit them to return back.

A conductor is a conductor. It doesn't matter (much) whether the charge carriers are holes or electrons. (Holes have higher effective mass and so generally lower mobility, which means the conductance is higher ... if I remember correctly.)

[Moreno]

1 hour ago, Strange said:

A conductor is a conductor. It doesn't matter (much) whether the charge carriers are holes or electrons. (Holes have higher effective mass and so generally lower mobility, which means the conductance is higher ... if I remember correctly.)

That's true. But hole conductor conducts only those electrons which lay below conduction band. They will flow in opposite directions with free electrons in metals when electric field is applied.

Edited January 17, 2019 by Moreno

[Strange]

1 hour ago, Moreno said:

That's true. But hole conductor conducts only those electrons which lay below conduction band. They will flow in opposite directions with free electrons in metals when electric field is applied.

I don't understand what you are saying. But if you have something that is conductor because of either free holes or free electrons, it will be a conductor that carries current. That current can flow from a metal wire (electrons as charge carriers) into the semiconductor (holes as charge carriers) and into another metal wire. If that were not true, then transistors would not work.

So if you try and make a capacitor by separating two pieces of metal with a material that has holes as charge carriers, then you will end up with a resistor (with very low resistance).

[Moreno]

34 minutes ago, Strange said:

I don't understand what you are saying. But if you have something that is conductor because of either free holes or free electrons, it will be a conductor that carries current. That current can flow from a metal wire (electrons as charge carriers) into the semiconductor (holes as charge carriers) and into another metal wire. If that were not true, then transistors would not work.

So if you try and make a capacitor by separating two pieces of metal with a material that has holes as charge carriers, then you will end up with a resistor (with very low resistance).

I meant not a dielectric capacitor, but a supercapacitor similar to those which use ionically conducting electrolyte. Instead of ions we have holes and in place of electolyte we have a P-type hole conductor.

Current will not flow into semiconductor if work function of metal is higher than that of semiconductor. Electrons always flow from lower to higher workfunction material.

I think the most difficult here is to predict how different materials will behave at nanoscales typical to ultracapacitors. Some sources claim that workfunction is often more related to contact surfaces than to the bulk material properties.

Edited January 17, 2019 by Moreno

[Strange]

14 minutes ago, Moreno said:

I meant not a dielectric capacitor, but a supercapacitor similar to those which use ionically conducting electrolyte. Instead of ions we have holes and in place of electolyte we have a P-type hole conductor.

The electrolyte is one of the electrodes of the capacitor. Is that what you are suggesting: to use the semiconductor as one of the electrodes? What would the insulating layer be?

 

[Moreno]

10 minutes ago, Strange said:

The electrolyte is one of the electrodes of the capacitor. Is that what you are suggesting: to use the semiconductor as one of the electrodes? What would the insulating layer be?

 

There is no need for insulating material as difference in work functions serve as an "insulator" by itself.

[Moreno]

Well, I think that even if that type of supercapacitor is going to be "leaky" and wouldn't be able to store charge for a long periods of time, it still could be useful in some particular areas. For example brake energy recuperation or DC/DC conversion.