716 mV Open‐Circuit Voltage with Fully Screen‐Printed p‐Type Back Junction Solar Cells Featuring an Aluminum Front Grid and a Passivating Polysilicon on Oxide Contact at the Rear Side

Abstract

This article reports the recent progress of p-type back junction solar cells featuring an aluminum front grid and an n þ-type passivating polysilicon on oxide (POLO) contact at the cell rear side. The best cell has an efficiency of 22.6% and an open-circuit voltage of 716 mV, independently confirmed by Institute for Solar Energy Research Hamelin (ISFH) CalTeC. The cell area is 244.5 cm 2. The increase in the SiN x capping layer thickness at the cell rear side reduces the deterioration of passivation quality of the POLO contact by screen-printed silver. This increases the open-circuit voltage by 22 mV compared with cells with a thinner nitride layer thickness. The investigation with scanning electron microscopy shows that the damage of the POLO contacts underneath the screen-printed metal contacts is avoided by increasing the SiN x capping layer thickness. A contact resistivity of 2 mΩ cm 2 is measured using the transfer length method.

Firing-Stable PECVD SiOxNy/n-Poly-Si Surface Passivation for Silicon Solar Cells

“…Passivating contacts based on SiO x /polysilicon (SiO x /poly-Si) layer stacks − are a promising technology for next-generation high-efficiency industrial silicon solar cells potentially succeeding mainstream passivated emitter and rear cells (PERCs) and bifacial PERC+ solar cells. , An outstanding passivation quality in combination with a good contact resistivity are the key advantages of SiO x /poly-Si contacts, which significantly reduce the recombination losses at metal fingers as well as of the phosphorus-doped emitter and hence exhibit a higher efficiency potential compared to presently around 23% efficient industrial PERC and PERC+ solar cells. − Solar cell efficiencies between 22.5 and 24.5% were demonstrated applying the SiO x /poly-Si contacts to industrial solar cell concepts such as tunnel oxide passivated contact (TOPCon), , monopoly, POLO-BJ, and POLO-IBC, whereas lab-type POLO2 IBC and TOPCon cells obtain up to 26.1% efficiency. The acronym polysilicon on oxide (POLO) stands for “poly-Si on oxide,” whereas TOPCon denotes “tunneling oxide passivating contact” .…”

A round Robin-Highliting on the passivating contact technology

“…Considering this by using a different Ag paste (ISFH-Ag), excellent mean values for the best group of 2 mVcm 2 is reached. The ISFH values are obtained on-site from a different experiment on comparable layers [10].…”

Sputtered Phosphorus‐Doped poly‐Si on Oxide Contacts for Screen‐Printed Si Solar Cells

“…This passivation and firing process were demonstrated to allow for efficient screen-printed solar cells that have poly-Si-based passivating contacts. [40,41] We derive the implied open-circuit voltage at 1 sun illumination (iV oc ) and the prefactor of the recombination current density at the surface ( J 0s ) from lifetime measurements at five different wafer positions with a quasisteady-state photoconductance measurement tool (Sinton Instruments WCT-120). [18] We use the transient analysis method, set the optical factor to 0.6 before hydrogenation and 0.9 after hydrogenation to accommodate changes in optics due to the deposited dielectric layer, and use the slope method from Kane and Swanson for the determination of J 0s .…”

“…This passivation and firing process were demonstrated to allow for efficient screen‐printed solar cells that have poly‐Si‐based passivating contacts. [ 40,41 ]…”