Research progress in doped absorber layer of CdTe solar cells

CdTe thin film solar cell, as an outstanding representative of the second-generation solar cells, has been produced and applied on a large scale. However, due to the low concentration of photogenerated carriers and short lifetime of minority carriers in its absorber layer, the open-circuit voltage and filling factor of the cell is limited and the further improvement of the cell power conversion efficiency is hindered. Various strategies and techniques such as doping, passivation, adding buffer and electron reflecting layers are commonly used to improve the defects and deficiencies of the CdTe absorber layer. In this paper, the relationship between p-type doping and non-p-type doping (passivation, buffer layer and electron reflection) is analyzed. An attempt is made to summarize the mechanism and pathway of efficient doping of CdTe from a large amount of published literature. After reviewing the recently CdTe absorber layer doping research in terms of doping mechanism, precursor selection, quantification and distribution, and doping process. It obtained that the qualitative and quantitative studies of key impurity elements, optimization of doping precursors, and new non-p-type doping elements are the future directions of doping research. Finally, this paper prospects for CdTe absorber layer doping in regard to the synthesis of absorber layer composites.