Dresden 2020 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 41: Perovskite and photovoltaics III (joint session HL/CPP)
HL 41.5: Talk
Wednesday, March 18, 2020, 10:30–10:45, POT 251
How does strain impact the solar cell performance at grain boundaries? — •Michael Stuckelberger1, Irene Calvo-Almazán2, Martin Holt2, Megan Hill3, Siddharth Maddali2, Mariana Bertoni4, Xiaojing Huang5, Hanfei Yan5, Evgeny Nazaretski5, Yong Chu5, Andrew Ulvestad2, and Stephan Hruszkewycz2 — 1DESY, Hamburg, Germany — 2ANL, Lemont IL, USA — 3Northwestern University, Evanston IL, USA — 4ASU, Tempe AZ, USA — 5BNL, Upton NY, USA
Grain boundaries (GB) often limit the conversion efficiency of polycrystalline solar cells. Strain is particularly detrimental there, as it enhances the defect concentration and band fluctuations, leading to increased recombination rates. Unfortunately, standard methods cannot easily measure the strain distribution in working thin-film devices.
Based on nanodiffraction experiments, we demonstrate the assessment of the strain distribution at sub-100-nm resolution. In a multimodal detector design, we combined nanodiffraction with X-ray fluorescence (XRF) and X-ray beam induced current (XBIC) measurements. Mapping individual grains, this enabled us to correlate point-by-point the strain with composition and performance within grains and at GB.
In CIGS solar cells, we found that the strain increases towards GB, which is accompanied by an increase of the charge collection efficiency. In contrast, we found a decreasing lattice constant towards GB in CdTe solar cells. Similar correlative experiments are ongoing on perovskite solar cells, and we will present the latest results.