Details

Autor(en) / Beteiligte

• Jensen, Soren A.
• Glynn, Stephen
• Kanevce, Ana
• Dippo, Pat
• Li, Jian V.
• Levi, Dean H.
• Kuciauskas, Darius

Titel

Beneficial effect of post-deposition treatment in high-efficiency Cu(In,Ga)Se2 solar cells through reduced potential fluctuations

Ist Teil von

• Journal of applied physics, 2016-08, Vol.120 (6)

Ort / Verlag

United States: American Institute of Physics (AIP)

Erscheinungsjahr

2016

Quelle

American Institute of Physics (AIP) Journals

Beschreibungen/Notizen

• World-record power conversion efficiencies for Cu(In,Ga)Se2 (CIGS) solar cells have been achieved via a post-deposition treatment with alkaline metals, which increases the open-circuit voltage and fill factor. We explore the role of the potassium fluoride (KF) post-deposition treatment in CIGS by employing energy- and time-resolved photoluminescence spectroscopy and electrical characterization combined with numerical modeling. The bulk carrier lifetime is found to increase with post-deposition treatment from 255 ns to 388 ns, which is the longest charge carrier lifetime reported for CIGS, and within ~40% of the radiative limit. We find evidence that the post-deposition treatment causes a decrease in the electronic potential fluctuations. These potential fluctuations have previously been shown to reduce the open-circuit voltage and the device efficiency in CIGS. Additionally, numerical simulations based on the measured carrier lifetimes and mobilities show a diffusion length of ~10 um, which is ~4 times larger than the film thickness. Furthermore, carrier collection in the bulk is not a limiting factor for device efficiency. By considering differences in doping, bandgap, and potential fluctuations, we present a possible explanation for the voltage difference between KF-treated and untreated samples.