| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 78017 | Solar Energy Materials and Solar Cells | 2014 | 10 Pages |
•An effective method for making an ohmic back contact to CdTe without wet etching.•The Cu to Te ratio is precisely controlled by the Te and Cu film thickness.•Enhanced efficiency and stability were got using optimized Te/Cu buffer.•Enhanced device stability can be attributed to the mediation of Cu diffusion by Te.•11.1% efficiency was achieved using 0.9 µm CdTe and Te/Cu bi-layer buffer.
A buffer layer based on a Te/Cu bi-layer useful for forming ohmic contact to p-CdTe has been developed for application in CdS/CdTe solar cells. The bi-layer buffer was prepared by vapor deposition and a thermal annealing (~200 °C) was required for activation. Enhanced efficiency and stability were obtained by optimizing the Cu/Te compositions and the thermal activation conditions. Characterization by XRD, XPS, and PL indicates that under the thermal activation conditions Cu diffuses rapidly in the Te without forming CuxTe compounds. The enhanced stability can be attributed to the mediation of Cu diffusion into CdTe by the Te layer. The Te/Cu buffers are particularly useful for the fabrication of ultra-thin CdS/CdTe solar cells.
Graphical abstractA contact buffer based on a Te/Cu bi-layer for forming ohmic contact to p-CdTe has been developed for application in CdS/CdTe solar cells. The bi-layer structure enables a better control of Cu diffusion in the back contact Te-rich region as well as Cu penetration into bulk CdTe film, providing the necessary balance in Cu concentrations in these regions. With optimized Cu/Te compositions and thermal activation conditions, much improved efficiency and stability have been obtained. The Te/Cu buffers are particularly useful for the fabrication of ultra-thin CdS/CdTe solar cells.Figure optionsDownload full-size imageDownload as PowerPoint slide
