High-efficiency pin-type Amorphous Si Solar Cells Fabricated with a Low-electron-affinity Buffer Layer on the Front Electrode

A strategy based on the reduction of absorption loss in the front doping layer and enhancement of the internal electric field in the intrinsic amorphous Si absorber layer attained by band lifting of the front doping layer is proposed. To demonstrate the strategy, we inserted a nitrogen-doped ZnO (ZnO:Al:N) buffer between the front transparent electrode and the front doped layer during the fabrication of a pin-type a-Si solar cell. We found a conditional improvement of solar cell performance that depended on the conductivity and bandgap of the front doped layer. In-depth discussion of the experimental results suggests further promising efficiency enhancement of amorphous Si solar cells by employing a low electron affinity buffer layer on the front electrode.