Composition and electronic structure of SiOx/TiOy/Al passivating carrier selective contacts on n‑type silicon solar cells

verfasst von

Christoph Flathmann, Tobias Meyer, Valeriya Titova, Jan Schmidt, Michael Seibt

Abstract

Carrier-selective and passivating SiO_x/TiO_y heterocontacts are an attractive alternative to conventional contacts due to their high efficiency potentials combined with relatively simple processing schemes. It is widely accepted that post deposition annealing is necessary to obtain high photovoltaic efficiencies, especially for full area aluminum metallized contacts. Despite some previous high-level electron microscopy studies, the picture of atomic-scale processes underlying this improvement seems to be incomplete. In this work, we apply nanoscale electron microscopy techniques to macroscopically well-characterized solar cells with SiO_x/TiO_y/Al rear contacts on n-type silicon. Macroscopically, annealed solar cells show a tremendous decrease of series resistance and improved interface passivation. Analyzing the microscopic composition and electronic structure of the contacts, we find that partial intermixing of the SiO_x and TiO_y layers occurs due to annealing, leading to an apparent thickness reduction of the passivating SiO_x. However, the electronic structure of the layers remains clearly distinct. Hence, we conclude that the key to obtain highly efficient SiO_x/TiO_y/Al contacts is to tailor the processing such that the excellent chemical interface passivation of a SiO_x layer is achieved for a layer thin enough to allow efficient tunneling through the layer. Furthermore, we discuss the impact of aluminum metallization on the above mentioned processes.

Organisationseinheit(en)

Institut für Festkörperphysik

Externe Organisation(en)

Georg-August-Universität Göttingen
Institut für Solarenergieforschung GmbH (ISFH)

Typ

Artikel

Journal

Scientific reports

Band

2023

ISSN

2045-2322

Publikationsdatum

2023

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Allgemein

Ziele für nachhaltige Entwicklung

SDG 7 – Erschwingliche und saubere Energie

Elektronische Version(en)

https://doi.org/10.1038/s41598-023-29831-2 (Zugang: Offen)