Diodes and low grade thermal energy harvesting

[ADesilets]

TL;DR

Be it IR photocurrent or dark current, there's always a use for current.

Infrared is ubiquitous and to do with dark current -> real meters have finite resistance, no real meter is a superconductor, if you can measure dark current: there's emf.

Since we can measure and quantify 0 bias dark current generation and we can see the measurements certified on manufacturers data sheets we should be looking at doing something with it.

For current to flow through a finite resistance it has to be propelled by EMF. In my experience, you can charge capacitors with dark current, in fact you have to if you want to have any chance of measuring the EMF behind it.

Main issue is that with diodes I have access to they are still tuned to SWIR and the real energy harvesting starts in MWIR and LWIR.

I'm at a loss, most of the MCT diodes are 1000's of $ a piece and InGaAs and PbSe diodes are cheaper but not exactly cheap either.

Ideally I'd like to solder together a series-parallel MWIR or LWIR harvesting panel but need to figure out a way to get access to 4-10 uM harvesting diodes for a reasonable or a suggestion on how to modify something else to get access to those bands.

 

[Dale]

Sounds like a financial problem. You should probably reach out to a venture capitalist.

 

[Baluncore]

Main issue is that with diodes I have access to they are still tuned to SWIR and the real energy harvesting starts in MWIR and LWIR.

There is little energy at those wavelengths because the voltage is low.

Electron energy can be specified in eV.
Longer wavelengths have lower energy, lower eV.
Given wavelength in μm; Energy; eV = 1.23984 / λ μm
Infrared energy ranges from 1.653 eV to 0.00124 eV

Near IR: 0.75 μm to 1.4 μm : 1.653 eV to 0.886 eV
SW IR: 1.4 μm to 3 μm : 0.886 eV to 0.413 eV
MW IR: 3 μm to 8 μm : 0.413 eV to 0.155 eV
LW IR: 8 μm to 15 μm : 0.155 eV to 0.083 eV
Far IR: 15 μm to 1,000μm : 0.083 eV to 0.00124 eV

From that you can see that MW IR and LW IR have low energy and low voltage. You would need very many PN junctions in series to produce a useful voltage.

 

[ADesilets]

It's fine that the energy levels are low. I've got no expectation off matching a solar panel at noon. My main thought is that the power available indoors is probably better in the IR spectrum than what indoor solar panels are tuned to.

 

[Baluncore]

My main thought is that the power available indoors is probably better in the IR spectrum than what indoor solar panels are tuned to.

Solar panels do not work in the dark. They are designed to operate at visual wavelength, in sunlight.

Indoors, there will be thermal radiation from the surrounding structure. You know it has a temperature of about 20°C, so you can work out the black body radiation curve; λpeak = 9.898 um, in the LW IR.
Using eV = 1.23984 / λ μm, we get photon energy, eV = 0.125 V, at the peak of the BB curve. You will need more than 8 PN junctions per volt.

Don't forget your panel will be at equilibrium with the surroundings, radiating as much energy to the room as the room does to the panel. Have you thought of how you will cool the panel to reduce re-radiation losses?