Regensburg 2022 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 27: Focus Session: Perspectives in Cu(In,Ga)Se 1

HL 27.3: Vortrag

Donnerstag, 8. September 2022, 10:30–10:45, H33

Role of Na in interconnection between chemical composition and electrical properties of grain boundaries in Cu(In, Ga)Se2 — •Azam Karami¹, Marcin Morawski², Heiko Kempa², Roland Scheer², and Oana Cojocaru-Mirédin¹ — ¹RWTH Aachen University, Aachen, Germany — ²Martin-Luther-Universität Halle-Wittenberg, Halle, Germany

Nowadays, the polycrystalline Cu(In,Ga)Se2 thin-film solar cells have attained increased interest due to their lower costs and higher cell efficiency in energy conversion. These polycrystalline absorbers contain a large ratio of grain boundaries which can be detrimental (increase in recombination activity compared to the bulk), neutral (no change in electrical properties relative to grains) or benign (increase in electrical properties) for the cell performance. In the present work, different techniques such as atom probe tomography and electron backscattered diffraction are used to investigate different grain boundaries in order to illustrate the relation between the chemical composition and the electrical properties of the grain boundaries. It is shown that the elemental changes at the grain boundaries such as Cu depletion, In enrichment and segregation of alkali dopants like Na, can directly affect their beneficial behavior in favor of cell performance. The experimental findings prove the significant role of Na addition in improving the cell parameters such as open circuit voltage and fill factor. Although it is also shown that the excessive addition of Na dopant can have a detrimental effect on the cell efficiency by increasing the density of dislocations and interference of deep defects with dopants.