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Optoelectronic Enhancement of Ultrathin CuIn 1–x Ga x Se 2 Solar Cells by Nanophotonic Contacts
Author(s) -
Yin Guanchao,
Knight Mark W.,
van Lare MarieClaire,
Solà Garcia Maria Magdalena,
Polman Albert,
Schmid Martina
Publication year - 2017
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.201600637
Subject(s) - materials science , optoelectronics , solar cell , layer (electronics) , absorption (acoustics) , nanophotonics , current density , optics , nanotechnology , composite material , physics , quantum mechanics
CuIn 1– x Ga x Se 2 (CIGSe) solar cells have achieved record efficiency values as high as 22.6% for small areas, with module efficiency values of 16.5%. However, for economic viability these values must be achieved with reduced material consumption (especially indium), which requires reducing the CIGSe absorber thickness from 2000–3000 nm to below 500 nm. Soft‐imprinted SiO x nanoparticles (NPs) beneath a conformal CIGSe layer enable this thickness reduction. Optically, they enhance the absorption of light through Fabry–Pérot and waveguided resonances within the CIGSe layer, preventing current loss. For CIGSe solar cells on ITO with an absorber thickness of only 390 nm and a nanophotonic contact the current density ( J sc ) increases from 25.7 to 32.1 mA cm −2 . At the same time, the nanopatterned contact reduces the back barrier, leading to an increased open‐circuit voltage (518 to 558 mV) and fill factor (50.7% to 55.2%). Combined, these effects increase the efficiency value from 6.8% to 10.0% for this initial demonstration. With the addition of an antireflection coating, the champion NP‐enhanced cell achieves a J sc of 34.0 mA cm −2 , corresponding to 93% of the J sc achieved by the thick world‐record cell. This result shows that optoelectronic nanopatterning provides a path to high efficiency cells with reduced materials consumption.