| AVS 65th International Symposium & Exhibition | |
| Thin Films Division | Monday Sessions |
| Session TF-MoA |
| Session: | IoT Session: Thin Films for Photovoltaics |
| Presenter: | John Walls, Loughborough University, UK |
| Authors: | T.A.M. Fiducia, Loughborough University, UK A. Abbas, Loughborough University, UK K. Li, University of Oxford, UK C.R.M. Grovenor, University of Oxford, UK A. Munshi, Colorado State University K.L. Barth, Colorado State University W.S. Sampath, Colorado State University J.M. Walls, Loughborough University, UK |
| Correspondent: | Click to Email |
Thin film polycrystalline Cadmium Telluride solar cells are the lowest cost solar technology. Recent improvements in the device architecture have increased device conversion efficiency and lowered costs still further. The traditional semi-absorbing cadmium sulphide window layer has been replaced with higher band gap alternatives such as magnesium-doped zinc-oxide (MZO). Also Selenium has been added to the near-junction interface region in the CdTe absorber layer which becomes graded during the cadmium chloride activation process and increases carrier lifetime. In this paper we report on microstructural and composition studies using STEM and EDX on device cross-sections along with the use of Nano-SIMS to provide 3-Dimensional chemical maps of the cells at high resolution and sensitivity. These microstructural analyses are correlated with electrical measurements from the devices. The analysis of chlorine and selenium in these cells reveals the different types of diffusion modes involved in 3 dimensions. It provides new insights into the passivation mechanisms at work in grain boundaries. It also provides the first direct evidence for passivation of incoherent twin facets and incorporation of chlorine and selenium in grain interiors. Improved understanding of the ways these new devices work will determine how they may be improved still further.