Abstracts Book - IMRC 2018

• SC4-O021 Invited Talk
ELECTRONIC AND CHEMICAL STRUCTURE OF ALTERNATIVE
BUFFERS AND THEIR INTERFACES IN THIN-FILM SOLAR CELLS
Clemens Heske 1,2
1 Karlsruher Institut für Technologie, Institute for Photon Science and Synchrotron Radiation,
Germany. 2 University of Nevada, Las Vegas, Chemistry & Biochemistry, United States.
Among the various technologies for thin-film solar cells, Cu(In,Ga)(S,Se)2-
(CIGSSe-) and CdTe-based systems rank prominently, having reached
conversion efficiencies well above 20%. Kesterite solar cells promise lower
material costs. Nevertheless, much remains to be understood and optimized, in
particular when alternative buffers (i.e., deviations the traditional CdS) are to be
employed.
Using electron and soft x-ray spectroscopy, it is possible to unravel (some of) the
secrets of the alternative buffer/absorber interfaces. This includes lab-based x-
ray and UV photoelectron spectroscopy, inverse photoelectron spectroscopy,
and x-ray-excited Auger electron spectroscopy. These techniques are
complemented by soft x-ray emission and absorption spectroscopy using highbrilliance
synchrotron radiation. While the electron-based techniques are very
surface-sensitive, the two synchrotron-based techniques are photon-in-photonout
techniques that probe the bulk region near the surface. In the talk,
experiments to gain insights into alternative buffer/absorber interfaces will be
presented, in particular in view of band alignment and intermixing behavior, and
the impact of these properties on the performance of corresponding solar cell
devices will be discussed.
Keywords: Thin-film solar cells, Interfaces, X-ray and Electron Spectroscopy
Presenting authors email: heske@kit.edu