Thin indium tin oxide layer development for crystalline silicon/perovskite two terminal tandem solar cell

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Journal Title

Journal ISSN

Volume Title

Insinööritieteiden korkeakoulu | Master's thesis

Date

2023-10-09

Department

Major/Subject

Energy Systems Track

Mcode

Degree programme

Nordic Master Programme in Innovative and Sustainable Energy Engineering (ISEE)

Language

en

Pages

65+2

Series

Abstract

ITO is widely regarded as the optimal TCO for serving as front window layer in PSK/c-Si tandem solar cells. It is known to effectively mitigate several stability issues present in perovskite solar cells while demonstrating excellent lateral conductivities and optical transparency across the entire solar spectrum. However, due to the damaging effects of traditional magnetron sputtering methods on the underlying cell precursor and the limited range of annealing temperatures viable for maintaining the stability of Perovskite Solar cells, realizing the full capability of ITO layer is constrained. This investigation focuses on developing and optimizing the front Indium Tin Oxide (ITO) layer properties for high-efficiency monolithic Perovskite/PERC tandem solar cells. The study employs two widely utilized industrial techniques, Magnetron Sputtering and Screen Printing for the deposition of ITO thin-films and subsequent metallization of silver front contacts. The sputtering process parameters, namely the carrier speed, 𝑂2:𝐴𝑟 ratio, and the sputter power were varied to obtain an optimized ITO layer, which exhibited a thickness of 53 𝑛𝑚, sheet resistance of 107 𝑜h𝑚/sq, mobility of 37𝑐𝑚2/𝑉𝑠, and 90 % average optical transparency between 400−1200 𝑛𝑚. A low contact resistivity of 5.4 𝑚W𝑐𝑚2 was achieved between the ITO and metal contacts which is the lowest reported value for ITO annealed at low temperature (140 °𝐶). Champion cells, featuring Perovskite on Ohmic substrate and 2T perovskite/PERC tandem cells, exhibited high 𝑉𝑂𝐶 values of 1.116 𝑉 and 1.75 𝑉 on 0.97𝑐𝑚2 cell aperture areas and cell efficiencies of 17.2 % and 23.85 %. Additionally, a large area (158.7 𝑐𝑚2) tandem cell was also fabricated which demonstrated an excellent 𝑉𝑂𝐶 of 1.75 𝑉. The results of this investigation demonstrates the versatility of ITO layer properties achievable at low-temperatures through Magnetron sputtering and underscores the potential of existing commercialized technologies for the fabrication of high-efficiency tandem solar cells.

Description

Supervisor

Halme, Janne

Thesis advisor

Coletti, Gianluca
Wu, Yu

Keywords

indium tin oxide, thin-film characterisation, magnetron sputtering, screen printing, tandem solar cells

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