Evaluation of advanced p‐PERL and n‐PERT large area silicon solar cells with 20.5% energy conversion efficiencies

Abstract

In this paper, we evaluate p-type passivated emitter and rear locally diffused (p-PERL) and n-type passivated emitter and rear totally diffused (n-PERT) large area silicon solar cells featuring nickel/copper/silver (Ni/Cu/Ag) plated front side contacts. By using front emitter p-PERL and rear emitter n-PERT, both cell structures can be produced with only a few adaptations in the entire process sequence because both feature the same front side design: homogeneous n + diffused region with low surface concentration, SiO 2 /SiN x :H passivation, Ni/Cu/Ag plated contacts. Energy conversion efficiencies up to 20.5% (externally confirmed at FhG-ISE Callab) are presented for both cell structures on large area cells together with power-loss analysis and potential efficiency improvements based on PC1D simulations. We demonstrate that the use of a rear emitter n-PERT cell design with Ni/Cu/Ag plated front side contacts enables to reach open-circuit voltage values up to 676 mV on 1-2 Ω cm n-type CZ Si. We show that rear emitter n-PERT cells present the potential for energy conversion efficiencies above 21.5% together with a strong tolerance to wafer thickness and bulk resistivity.

High-efficiency crystalline silicon solar cells: status and perspectives

“…This can be resolved with metal plating. [159][160][161] Thanks to the improved line conductivity and the different patterning technique, narrower and taller lines can be fabricated, reducing shading losses. Copper is often the metal of choice, offering attractive cost advantages.…”

SiO2Passivation Layer Grown by Liquid Phase Deposition for N-type Bifacial Silicon Solar Cells

“…LPD SiO 2 films passivated n-type bifacial silicon solar cells For the fabrication of silicon solar cells, the crystalline silicon is Czochralski (Cz) N-type silicon with a resistivity of 1-6 ȍ·cm, a thickness of 180 ȝm and an area of about 238.95 cm 2 . Fig.1 shows the schematic diagram of n-type bifacial silicon solar cell.…”

“…So far, many efforts have been devoted to make n-type silicon wafers into silicon solar cells [1,2,3], due to the fact that n-type silicon wafer is superior to p-type silicon wafer in many aspects, such as minority carrier lifetime, metal contaminate tolerance [4] and light-induced degradation [5]. The n-Pasha cell from ECN is a typical structure of n-type bifacial solar cell [6].…”

“…For the bifacial solar cells, the passivation quality of the highly-doped boron emitter and phosphorus back surface field has a great influence on the final cell performance. Currently, one of the most widely used passivation techniques for n-type bifacial solar cell production is thermally-grown SiO 2 capped with SiN x [2,3]. Though its surface passivation effect is excellent, it requires expensive equipment, high growth temperature and a long process step.…”

Challenges facing copper‐plated metallisation for silicon photovoltaics: Insights from integrated circuit technology development

“…Furthermore, in the case of the Pluto LDSE cells, crystal defects in the n + Si region under the contact may have also provided effective gettering sites for any entrant Cu. Although this apparent out‐diffusion/gettering of Cu to heavily‐doped n‐type surfaces may be fortuitous for SE p‐type solar cells, the case may be different for n‐type Cu‐plated PERT cells where Cu precipitates may form in the base of the cell …”