Simulation-based roadmap for the integration of poly-silicon on oxide contacts into screen-printed crystalline silicon solar cells

Christian N Kruse,Felix Haase,Bianca Lim,Sören Schäfer,Rolf Brendel,Henning Schulte-Huxel,Byungsul Min,Robby Peibst,Thorsten Dullweber,Verena Mertens

doi:10.1038/s41598-020-79591-6

Christian N Kruse, Felix Haase + Show 8 more

Open Access

https://doi.org/10.1038/s41598-020-79591-6

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Abstract

We present a simulation-based study for identifying promising cell structures, which integrate poly-Si on oxide junctions into industrial crystalline silicon solar cells. The simulations use best-case measured input parameters to determine efficiency potentials. We also discuss the main challenges of industrially processing these structures. We find that structures based on p-type wafers in which the phosphorus diffusion is replaced by an n-type poly-Si on oxide junction (POLO) in combination with the conventional screen-printed and fired Al contacts show a high efficiency potential. The efficiency gains in comparsion to the 23.7% efficiency simulated for the PERC reference case are 1.0% for the POLO BJ (back junction) structure and 1.8% for the POLO IBC (interdigitated back contact) structure. The POLO BJ and the POLO IBC cells can be processed with lean process flows, which are built on major steps of the PERC process such as the screen-printed Al contacts and the text{Al}_text{2 }text{O}_text{3 }/text{SiN } passivation. Cell concepts with contacts using poly-Si for both polarities (text{POLO}^2-concepts) show an even higher efficiency gain potential of 1.3% for a text{POLO}^2 BJ cell and 2.2% for a text{POLO}^2 IBC cell in comparison to PERC. For these structures further research on poly-Si structuring and screen-printing on p-type poly-Si is necessary.

Highlights

We present a simulation-based study for identifying promising cell structures, which integrate poly-Si on oxide junctions into industrial crystalline silicon solar cells
The poly-Si on oxide junction (POLO) back junction (BJ) and the POLO interdigitated back contact (IBC) cells can be processed with lean process flows, which are built on major steps of the passivated emitter and rear cells (PERC) process such as the screen-printed Al contacts and the Al2 O3 /SiN
We proposed in Ref.[11] the overcompensation concept, which can be applied for both POLO2 BJ and POLO2 IBC

Summary

Introduction

We present a simulation-based study for identifying promising cell structures, which integrate poly-Si on oxide junctions into industrial crystalline silicon solar cells. Numerous manufacturers have started (pilot) production of solar cells featuring POLO junctions or are producing similar cell concepts on rather small scale since some years with impressive r esults[7,8,9], these approaches are in strong competition with PERC and PERC+ as the “conventional” current mainstream Some reasons for this hard standing are an increased process complexity and an uncertainty on the efficiency potential of the respective new cell structures. The goal of our study is to identify cell structures that show a high efficiency potential along with potentially lean process flows From this discussion, a possible roadmap for industrializing p-type c-Si solar cells using POLO junctions is derived. A possible roadmap for industrializing p-type c-Si solar cells using POLO junctions is derived. (The experimental realization of the most promising cell structures will be the subject of future work.)

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