Liquid phase crystallized silicon – A holistic absorber quality assessment

In this paper, we report on the current status of absorber attributes in Liquid Phase Crystallized Silicon (LPC-Si) cells. To this end, an absorber doping series (ND = 2·1016/cm³ to 7·1017/cm³) and an absorber thickness variation (14 and 33µm) are evaluated. Best cells from the batches for these ser...

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Bibliographic Details
Published in:Solar energy materials and solar cells 2018-07, Vol.181, p.2-8
Main Authors: Sonntag, Paul, Bokalič, Matevž, Preissler, Natalie, Amkreutz, Daniel, Rech, Bernd, Topič, Marko
Format: Article
Language:English
Subjects:
Absorbers
Crop yield
Crystallization
Diffusion
Diffusion length
Doping
Fluids
Grain boundaries
LBIC
Liquid Phase Crystallization
Open circuit voltage
Photovoltaic cells
Quality assessment
Quality control
Short circuit currents
Short circuits
Silicon
Silicon solar cells
Surface recombination
Thin films
Thin-film
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Summary:In this paper, we report on the current status of absorber attributes in Liquid Phase Crystallized Silicon (LPC-Si) cells. To this end, an absorber doping series (ND = 2·1016/cm³ to 7·1017/cm³) and an absorber thickness variation (14 and 33µm) are evaluated. Best cells from the batches for these series showed open circuit voltages up to 640mV and fill factors above 70%. It is observed that for state-of-the-art cells, thicknesses over 15µm are not beneficial due to limited diffusion lengths. Lower absorber doping concentrations tend to yield longer intra-grain diffusion lengths (Ldiff) and better passivated grain boundaries, which may be due to lower impurity precipitation. The longer Ldiff leads to higher short circuit current densities which over-compensate a decrease in open circuit voltage and fill factor with regards to efficiency. Both front and rear surfaces are sufficiently passivated and at the current status the bulk lifetime has most potential for improvement. •LPC-Si cells on glass under investigation of absorber doping and thickness.•Diffusion lengths and inter-grain passivation both decrease with increasing doping.•Best effective diffusion lengths are 24–43µm for ND = 2.0·1016/cm³.•Front and rear surfaces of the cells are sufficiently passivated.•Surface recombination velocities are around 200cm/s.
ISSN:0927-0248
1879-3398
DOI:10.1016/j.solmat.2017.08.019