Open AccessTailored disorder: a self-organized photonic contact for light trapping in silicon-based tandem solar cells
Author(s) -
Hubert Hauser,
Kai Mühlbach,
Oliver Höhn,
Ralph Müller,
Sonja Seitz,
Jürgen Rühe,
Stefan W. Glunz,
Bénédikt Bläsi
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.390312
Subject(s) - materials science , silicon , optoelectronics , polystyrene , tandem , photonics , polymer , optics , nanoimprint lithography , polymer solar cell , trapping , scattering , solar cell , fabrication , composite material , medicine , ecology , physics , alternative medicine , pathology , biology
We present a process development leading to efficient rear side light trapping structures with the purpose of enhancing the infrared response of a silicon-based tandem solar cell. To this end, we make use of phase separation effects of two immiscible polymers, polystyrene and poly(methyl methacrylate), resulting in a non-periodic polystyrene structure on silicon with a well-defined size distribution. Onto this pattern, we evaporate silver as a scattering rear side mirror and contact layer. Average feature sizes and periods can be tuned by varying material properties (e.g. molar weights or ratios of the polymers) as well as processing conditions during the spin coating. This way a favorable pseudo period of approx. 1 µm for these disordered structure features was realized and successfully implemented into a silicon solar cell. The structure shows a ring-shaped scattering distribution which is beneficial for light trapping in solar cells. External quantum efficiency measurements show that a gain in short circuit current density of 1.1 mA/cm 2 compared to a planar reference can be achieved, which is in the same range as we achieved using nanoimprint lithography in a record triple-junction III/V on a silicon device.