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Passivation of all-angle black surfaces for silicon solar cells

Passivation of all-angle black surfaces for silicon solar cells
Passivation of all-angle black surfaces for silicon solar cells
Optical losses at the front surface of a silicon solar cell have a significant impact on efficiency, and as such, efforts to reduce reflection are necessary. In this work, a method to fabricate and passivate nanowire-pyramid hybrid structures formed on a silicon surface via wet chemical processing is presented. These high surface area structures can be utilised on the front surface of back contact silicon solar cells to maximise light absorption therein. Hemispherical reflectivity under varying incident angles is measured to study the optical enhancement conferred by these structures. The significant reduction in reflectivity (<2%) under low incident angles is maintained at high angles by the hybrid textured surface compared to surfaces textured with nanowires or pyramids alone. Finite Difference Time Domain simulations of these dual micro-nanoscale surfaces under varying angles supports the experimental results. In order to translate the optical benefit of these high surface area structures into improvements in device efficiency, they must also be well passivated. To this end, atomic layer deposition of alumina is used to reduce surface recombination velocities of these ultra-black silicon surfaces to below 30 cm/s. A decomposition of the passivation components is performed using capacitance-voltage and Kelvin Probe measurements. Finally, device simulations show power conversion efficiencies exceeding 21% are possible when using these ultra-black Si surfaces for the front surface of back contact silicon solar cells
0927-0248
444-453
Rahman, Tasmiat
e7432efa-2683-484d-9ec6-2f9c568d30cd
Bonilla, Ruy
137f64f8-ad84-4eed-99c0-30325effaa4c
Nawabjan, Amirjan
9e085c58-16c0-4ec5-bef2-28b0b30a84a0
Wilshaw, Peter
e289051a-5c0b-4600-84da-7ae8af1ebaf4
Boden, Stuart
83976b65-e90f-42d1-9a01-fe9cfc571bf8
Rahman, Tasmiat
e7432efa-2683-484d-9ec6-2f9c568d30cd
Bonilla, Ruy
137f64f8-ad84-4eed-99c0-30325effaa4c
Nawabjan, Amirjan
9e085c58-16c0-4ec5-bef2-28b0b30a84a0
Wilshaw, Peter
e289051a-5c0b-4600-84da-7ae8af1ebaf4
Boden, Stuart
83976b65-e90f-42d1-9a01-fe9cfc571bf8

Rahman, Tasmiat, Bonilla, Ruy, Nawabjan, Amirjan, Wilshaw, Peter and Boden, Stuart (2017) Passivation of all-angle black surfaces for silicon solar cells. Solar Energy Materials and Solar Cells, 160, 444-453. (doi:10.1016/j.solmat.2016.10.044).

Record type: Article

Abstract

Optical losses at the front surface of a silicon solar cell have a significant impact on efficiency, and as such, efforts to reduce reflection are necessary. In this work, a method to fabricate and passivate nanowire-pyramid hybrid structures formed on a silicon surface via wet chemical processing is presented. These high surface area structures can be utilised on the front surface of back contact silicon solar cells to maximise light absorption therein. Hemispherical reflectivity under varying incident angles is measured to study the optical enhancement conferred by these structures. The significant reduction in reflectivity (<2%) under low incident angles is maintained at high angles by the hybrid textured surface compared to surfaces textured with nanowires or pyramids alone. Finite Difference Time Domain simulations of these dual micro-nanoscale surfaces under varying angles supports the experimental results. In order to translate the optical benefit of these high surface area structures into improvements in device efficiency, they must also be well passivated. To this end, atomic layer deposition of alumina is used to reduce surface recombination velocities of these ultra-black silicon surfaces to below 30 cm/s. A decomposition of the passivation components is performed using capacitance-voltage and Kelvin Probe measurements. Finally, device simulations show power conversion efficiencies exceeding 21% are possible when using these ultra-black Si surfaces for the front surface of back contact silicon solar cells

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tasmiatrahman_solmat_2017.pdf - Accepted Manuscript
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More information

Accepted/In Press date: 26 October 2016
e-pub ahead of print date: 15 November 2016
Published date: February 2017
Organisations: Nanoelectronics and Nanotechnology

Identifiers

Local EPrints ID: 397727
URI: https://eprints.soton.ac.uk/id/eprint/397727
ISSN: 0927-0248
PURE UUID: ff1a1d6a-9a2b-4957-94be-8cc784fb4cd2
ORCID for Stuart Boden: ORCID iD orcid.org/0000-0002-4232-1828

Catalogue record

Date deposited: 23 Jan 2017 16:54
Last modified: 06 Jun 2018 12:43

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