Journal Article

FZJ-2018-00076

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Effect of topography-dependent light coupling through a near-field aperture on the local photocurrent of a solar cell

Cao, Z. (Corresponding author)FZJ* ; Ermes, M. ; Lehnen, S. ; Carius, R.FZJ* ; Bittkau, K. (Corresponding author)FZJ*

2018
RSC Publ. Cambridge

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Please use a persistent id in citations: doi:10.1039/C7CP06783F

Abstract: An aperture-type scanning near-field optical microscope (a-SNOM) is readily used for the optical and optoelectronic characterizations of a wide variety of chemical, biological and optoelectronic samples with sub-wavelength optical resolution. These samples mostly exhibit nanoscale topographic variations, which are related to local material inhomogeneity probed either by an optical contrast or by secondary effects such as photoconductivity or photoluminescence. To date, in the interpretation and evaluation of the measurement results from a-SNOM or derived methods, often only the local material inhomogeneity is taken into account. A possible influence of the optical interaction between the scanning probe and the surface topography is rarely discussed. In this paper, we present experimental and theoretical investigation of the effects of nanoscale topographic features on a-SNOM measurement results. We conduct local photocurrent measurements on a thin-film solar cell with an a-SNOM as the illumination source. A clear correlation between the photocurrent response and local topography is observed in all measurements with a signal contrast of up to ~30%, although the sample features homogeneous permittivity and electrical properties. With the help of finite-difference time-domain (FDTD) simulations, this correlation is reproduced and local light coupling is identified as the mechanism which determines the local photocurrent response. Our results suggest that a-SNOM-based measurements of any sample with material inhomogeneity will be superimposed by the local light-coupling effect if surface topography variation exists. This effect should always be taken into consideration for an accurate interpretation of the measurement results.

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Contributing Institute(s):

1. Photovoltaik (IEK-5)

Research Program(s):

1. 121 - Solar cells of the next generation (POF3-121) (POF3-121)
2. CHEETAH - Cost-reduction through material optimisation and Higher EnErgy outpuT of solAr pHotovoltaic modules - joining Europe’s Research and Development efforts in support of its PV industry (609788) (609788)

Appears in the scientific report 2018

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Database coverage:
; Allianz-Lizenz / DFG ; Current Contents - Physical, Chemical and Earth Sciences ; IF < 5 ; JCR ; NCBI Molecular Biology Database ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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