Anti-reflective Coatings for Multi-junction Solar Cells
Reuna, Jarno (2016)
Reuna, Jarno
2016
Teknis-luonnontieteellinen koulutusohjelma
Luonnontieteiden tiedekunta - Faculty of Natural Sciences
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Hyväksymispäivämäärä
2016-12-07
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201611244791
https://urn.fi/URN:NBN:fi:tty-201611244791
Tiivistelmä
This thesis studied anti-reflective (AR) coatings for multi-junction solar cells (MJSC). The focus was on fabrication and characterization of dielectric thin films for AR coatings.
In particular, the work focused on MgF2-based coatings and studying the effects of substrate temperature on the refractive index and mechanical properties of MgF2 films deposited by electron beam evaporation. Similarly, we studied the process parameters of nanoporous SiO2 deposited by plasma-enhanced chemical vapor deposition at different substrate temperatures and precursor gas ratios. Then for the two different spinnable siloxane coating, we studied parameters including spinning speed and lid position. The study revealed that MgF2 refractive index increases with substrate temperature until temperature of over 250 oC. For SiO2 the decrease in temperature and altered gas ratio generated porous structure that lowered the refractive index.
The characterization results were used to simulate and optimize four different AR coatings for triple-junction InGaP/GaAs/GaInNAsSb solar cell using Essential Macleod design program. The coatings were MgF2/TiO2, nanoporous SiO2 with TiO2, siloxane layer with TiO2 and a triple layer coating of MgF2/Al2O3/TiO2. The coatings were compared to the conventional SiO2/TiO2 AR coating. The coated cells were tested with solar simulator under AM1.5D spectrum and all coating designs showed proper functionality, thus promising more efficient coating designs with these materials.
In particular, the work focused on MgF2-based coatings and studying the effects of substrate temperature on the refractive index and mechanical properties of MgF2 films deposited by electron beam evaporation. Similarly, we studied the process parameters of nanoporous SiO2 deposited by plasma-enhanced chemical vapor deposition at different substrate temperatures and precursor gas ratios. Then for the two different spinnable siloxane coating, we studied parameters including spinning speed and lid position. The study revealed that MgF2 refractive index increases with substrate temperature until temperature of over 250 oC. For SiO2 the decrease in temperature and altered gas ratio generated porous structure that lowered the refractive index.
The characterization results were used to simulate and optimize four different AR coatings for triple-junction InGaP/GaAs/GaInNAsSb solar cell using Essential Macleod design program. The coatings were MgF2/TiO2, nanoporous SiO2 with TiO2, siloxane layer with TiO2 and a triple layer coating of MgF2/Al2O3/TiO2. The coatings were compared to the conventional SiO2/TiO2 AR coating. The coated cells were tested with solar simulator under AM1.5D spectrum and all coating designs showed proper functionality, thus promising more efficient coating designs with these materials.