Abstract
We investigated the effect of Na incorporation on the electronic properties of polycrystalline CuIn0.7Ga0.3Se2 thin films using scanning tunneling microscopy and spectroscopy. The tunneling spectra indicate a reduced in-gap density of states at grain boundaries and reveal a downward band-bending in Na-rich grain boundaries with respect to the adjacent grains, in agreement with our conductive atomic force microscopy data. It thus appears that Na passivates deep-level defects at grain boundaries and induces a downward band-bending there. Moreover, we provide evidence that Na passivates mainly Cu vacancy related defects. We suggest that the grain-boundary passivation, which reduces the recombination rate of photogenerated carriers, is at least of major importance in the well known Na-induced improvement in the efficiency of the corresponding solar cells.
Original language | English |
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Pages (from-to) | 448-452 |
Number of pages | 5 |
Journal | Physica Status Solidi - Rapid Research Letters |
Volume | 10 |
Issue number | 6 |
DOIs | |
State | Published - 1 Jun 2016 |
Bibliographical note
Publisher Copyright:© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Keywords
- Cu(In,Ga)Se
- electronic properties
- grain boundaries
- scanning tunneling spectroscopy