Title
Poly-crystalline silicon-oxide films as carrier-selective passivating contacts for c-Si solar cells
Author
Yang, G.
Guo, P.
Procel, P.
Weber, A.W.
Isabella, O.
Publication year
2018
Abstract
The poly-Si carrier-selective passivating contacts (CSPCs) parasitically absorb a substantial amount of light, especially in the form of free carrier absorption. To minimize these losses, we developed CSPCs based on oxygen-alloyed poly-Si (poly-SiOx) and deployed them in c-Si solar cells. Transmission electron microscopy analysis indicates the presence of nanometer-scale silicon crystals within such poly-SiOx layers. By varying the O content during material deposition, we can manipulate the crystallinity of the poly-SiOx material and its absorption coefficient. Also, depending on the O content, the bandgap of the poly-SiOx material can be widened, making it transparent for longer wavelength light. Thus, we optimized the O alloying, doping, annealing, and hydrogenation conditions. As a result, an extremely high passivation quality for both n-type poly-SiOx (J0¼3.0 fA/cm2 and iVoc¼740 mV) and p-type poly-SiOx (J0¼17.0 fA/cm2 and iVoc¼700 mV) is obtained. A fill factor of 83.5% is measured in front/back-contacted solar cells with both polarities made up of poly-SiOx. This indicates that the carrier transport through the junction between poly-SiOx and c-Si is sufficiently efficient. To demonstrate the merit of poly-SiOx layers’ high transparency at long wavelengths, they are deployed at the back side of interdigitated backcontacted (IBC) solar cells. A preliminary cell efficiency of 19.7% is obtained with much room for further improvement. Compared to an IBC solar cell with poly-Si CSPCs, a higher internal quantum efficiency at long wavelengths is observed for the IBC solar cell with poly-SiOx CSPCs, thus demonstrating the potential of poly-SiOx in enabling higher JSC.
Subject
Energy Efficiency
Energy
Energy / Geological Survey Netherlands
Efficiency
High resolution transmission electron microscopy
Nanostructured materials
Oxide films
Passivation
Polycrystalline materials
Semiconductor doping
Silicon compounds
Silicon oxides
Solar cells
Transmission electron microscopy
Absorption co-efficient
Free carrier absorption
High transparency
Internal quantum efficiency
Material deposition
Nano-meter scale
Poly-crystalline silicon
Transmission electron
Silicon solar cells
To reference this document use:
http://resolver.tudelft.nl/uuid:518ae187-a2c8-461a-af05-ad898fb1185a
DOI
https://doi.org/10.1063/1.5027547
TNO identifier
814326
Source
Applied Physics Letters, 112, 1-6
Document type
article