Dear Darya,

welcome,

You can refer to the articles of transparent condcutive oxides.

Trans-pert conductive oxide has wide gap to let most of the solar radiation pass through it. At the same time it contains high electron concentration making it behave as a degenerate semicondcutor. Such behavior is metal like and therefore such material can be used in place pf metalization layer where one want optical transparency like the case of optoelectronic devices interacting with light.

One of the most common material is the Tinoxide, indium tin oxide and to less extent ZnO.

In order to judge the suitability of ZnO as ETL in addition to high electron conductivity it must have a suitable energy and matching with active layer of the solar cells.

So, it is a matter of satisfying specific condition's for good operating device.

You can search with the keyword conductive oxides and electron transport layers.

Best wishes

Thank you Sir Abdelhalim Zekry

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