Optimization of plasmonic white paint back reflector for flat poly-SiOx passivated silicon solar cells

Optimization of plasmonic white paint back reflector for flat poly-SiOx passivated silicon solar cells

Choubey, Anjali (TU Delft Electrical Engineering, Mathematics and Computer Science)

Isabella, O. (mentor)
Santbergen, R. (mentor)

Delft University of Technology

Electrical Engineering | Sustainable Energy Technology

2019-02-21

Crystalline silicon (c-Si) has low absorption coefficient in the near infra-red spectrum(NIR), which results in transmission losses in this region. This means there is a need for a back reflector in c-Si solar cells to capture the NIR light. One of the easiest ways of capturing NIR light is by using a reflective metal layer deposited onto a surface texture. However, in some cases surface texture cannot be applied. Having a flat metal reflector does not accomplish effective absorption of the NIR light. To enable effective absorption of NIR light, Lambertian reflectors are needed, which have a reflectance (rback ) of 1 (100% reflectivity) and a diffuse angle (θd ) of 60°. Lambertian scattering can be accomplished to an extent by using a combination of plasmonic nanoparticles and white paint as back reflectors.
There have been many investigations where plasmonic back reflectors (PBR), white paint back reflectors (WPBR) and even plasmonic white paint back reflectors (PWPBR) have been used for enhancing absorption in thin-film solar cell technology. But there are not many instances where these reflectors are utilized in c-Si solar cells. Therefore, in this work plasmonic white paint back reflectors are optimized for poly-SiOx passivated c-Si solar cells. To accomplish this, first a detailed optical study was carried out to analyze various rback and θd combinations that can be obtained with different back reflectors. Then the back reflector combination that gave a decent rback and θd combination where then chosen for solar cell simulations. With the help of simulations, external quantum efficiency (EQE) and implied photo-current gain was quantified for combinations with high rback and θd in comparison with normal silver metal back reflectors. The solar cell stack that generated substantial optical gain with the help of simulations were then fabricated and measured. Measurements revealed significant EQE gain with all PBR, WPBR and PWPBR in comparison with Ag metal BR. Form this research work it was inferred that for poly-SiOx passivated flat c-Si solar cells, PWPBR gives highest EQE in the NIR. However, this is only the case when as thin as possible spacer layers are used.

Plasmonic white paint back reflectors
flat poly-SiOx passivated c-Si solar cells
EQE gain
near infra-red region

http://resolver.tudelft.nl/uuid:2fb4e5d7-b1b3-4ddb-8c15-f94ac927817e

2019-08-21

Student theses

master thesis

© 2019 Anjali Choubey