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Origin of passivation in hole-selective transition metal oxides for crystalline silicon heterojunction solar cells

Published online by Cambridge University Press:  19 December 2016

Luis G. Gerling Open the ORCID record for Luis G. Gerling [Opens in a new window] ,
Cristobal Voz Open the ORCID record for Cristobal Voz [Opens in a new window] ,
Ramón Alcubilla Open the ORCID record for Ramón Alcubilla [Opens in a new window]  and
Joaquim Puigdollers Open the ORCID record for Joaquim Puigdollers [Opens in a new window]
Luis G. Gerling*
Affiliation:
Electronic Engineering Department, Universitat Politècnica de Catalunya, Barcelona 08034, Spain; and Centre de Recerca en Nanoenginyeria, Universitat Politécnica de Catalunya, Barcelona 08028, Spain
Cristobal Voz
Affiliation:
Electronic Engineering Department, Universitat Politècnica de Catalunya, Barcelona 08034, Spain; and Centre de Recerca en Nanoenginyeria, Universitat Politécnica de Catalunya, Barcelona 08028, Spain
Ramón Alcubilla
Affiliation:
Electronic Engineering Department, Universitat Politècnica de Catalunya, Barcelona 08034, Spain; and Centre de Recerca en Nanoenginyeria, Universitat Politécnica de Catalunya, Barcelona 08028, Spain
Joaquim Puigdollers
Affiliation:
Electronic Engineering Department, Universitat Politècnica de Catalunya, Barcelona 08034, Spain; and Centre de Recerca en Nanoenginyeria, Universitat Politécnica de Catalunya, Barcelona 08028, Spain
*
a) Address all correspondence to this author. e-mail: guillermo.gerling@upc.edu
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Abstract

Transition metal oxides (TMOs) have recently demonstrated to be a good alternative to boron/phosphorous doped layers in crystalline silicon heterojunction solar cells. In this work, the interface between n-type c-Si (n-Si) and three thermally evaporated TMOs (MoO3, WO3, and V2O5) was investigated by transmission electron microscopy, secondary ion-mass, and x-ray photoelectron spectroscopy. For the oxides studied, surface passivation of n-Si was attributed to an ultra-thin (1.9–2.8 nm) SiOx∼1.5 interlayer formed by chemical reaction, leaving oxygen-deficient species (MoO, WO2, and VO2) as by-products. Carrier selectivity was also inferred from the inversion layer induced on the n-Si surface, a result of Fermi level alignment between two materials with dissimilar electrochemical potentials (work function difference Δϕ ≥ 1 eV). Therefore, the hole-selective and passivating functionality of these TMOs, in addition to their ambient temperature processing, could prove an effective means to lower the cost and simplify solar cell processing.

Keywords

photovoltaicpassivationoxide
Type
Invited Papers
Information
Journal of Materials Research , Volume 32 , Issue 2 , 27 January 2017 , pp. 260 - 268
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Copyright
Copyright © Materials Research Society 2016 

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