Dear Sambuddha Majumder ,

The concept of the stacking of the solar cell layers is that the top layer facing the solar radiation is the window layer with the higher energy gap while the bottom layer is major absorber layer having the lower bandgap.

Accordingly, the outer laying facing the sun must be of higher energy gap while the core is the lower bandgap.

Best wishes

Dear Sambuddha Majumder ,

The concept of the stacking of the solar cell layers is that the top layer facing the solar radiation is the window layer with the higher energy gap while the bottom layer is major absorber layer having the lower bandgap.

Accordingly, the outer laying facing the sun must be of higher energy gap while the core is the lower bandgap.

Best wishes

Thank you for your answer Abdelhalim Zekry sir .

Could you please provide me some paper or article that mentions that. I have searched a lot but could not find any proper explanation for this in context of the radial solar cells.

However, there are papers who have simulated and designed solar cells with the wider bandgap material as the core material and vice versa.

It depends what you want to do with the structure and the size of the structure. Like Dr. Zekry has indicated, normally the larger bandgap material is on the top or outside as the window/electrode layer. Also, the large bandgap material is used as passivation layer to eliminate the surface states of the absorber layer (e.g., GaAs in your case). However, when the structure is very small, they cannot be treated as two layers but a new structure with distinctly different electronic structures from either of them. The order may result in either electrons on the outer shell or holes, which suits for different applications. See for instance, Article “Quantum Coaxial Cables” for Solar Energy Harvesting