ITO front contact

fdtd

#1

Hi,

I’m trying to obtain optical generation rate of a unit solar cell with indium tin oxide front contact. The Si substrate is etched in the form of a inverse pyramid and then there’s a deposited thin layer of indium tin oxide.

My question is related to properties of ITO. According to the simulation result, ITO seems like absorbing photons and generating electron-hole pairs. I’m not familiar with the properties of ITO. So, I wonder if ITO’s ehp generation is a physical phenomenon or it’s just due to solar generation algorithm which considers that every absorbed photon generates an ehp.

If latter is the case, I guess it would lead to an erroneous Jsc as the solar generation windows includes ITO contact. So, what can I do to exclude this additional current ?

2D_Pyramid.fsp (318.9 KB)

Thanks


#2

Hi @mehmet-efe.gumus,

I’m not too familiar with the properties of ITO, but my understanding is it is often used as a transparent electrode, so I would assume it is not used in the photovoltaic process.

Regarding the calculation of the generation rate and current, as discussed in the methodology page, it is based on the calculation of the absorption in the volume defined by the analysis group and the monitors it includes. The power absorbed is calculated by:

E is given by the field monitor and eps by the index monitor. Since these monitors include the silicon and the ITO, it will include the eventual absorption in ITO.

To calculate the generation rate, we assume all absorbed photons generate an electron/hole pair. Then, Jsc is calculated assuming all electron-hole pair contributes to photocurrent.

As you mentioned, if the absorption in ITO doesn’t contribute to the photovoltaic process, the generation rate and Jsc calculation are incorrect. That said, you can use a similar method as the one described in the absorption per unit volume - multiple materials to create a filter and only take into account the contribution of silicon.

I hope this will help.


#3

Hi @gbaethge

Thanks for the help ! I will take a look at the “absorption per unit volume”. Meanwhile, I got around the problem with a script in which I equate the G matrix to zero on mesh nodes which correspond to ITO. In this way, Jsc had a slight decrease of 0.6 mA / cm2 .

remove_electrode_generation.lsf (948 Bytes)


#4

You’re welcome, @mehmet-efe.gumus :slight_smile: I think the idea is very similar, in the example I mentioned, A filter is created to set to 0 the contribution of the material you don’t want to take into account.