Large area co‐plated bifacial n‐PERT cells with polysilicon passivating contacts on both sides

Abstract

In this work, we show the integration of polysilicon-based passivating contacts in plated bifacial n-type PERT (passivated emitter and rear totally diffused) solar cells.We show the viability of n-PERT cells using two-side passivating contacts with twoside plated nickel/silver metallization. Compared with commercially available "TOPCon" cells with rear side passivated contacts only, n-PERT cells with both side passivated contacts should enable the exploitation of the full potential of passivated contacts. We show that both n-poly and p-poly were applied and co-plated successfully on both sides of n-PERT solar cells. Considering the potential parasitic absorption losses on the front side of the device originating from p-poly, we applied selective p-poly by patterning. We compared two patterning methods for front side polysilicon: the masking and etch approach using inkjet printing and a simple and cost-effective patterning method using UV laser oxidation. A best efficiency of 22.7% has been achieved with these cells so far on large area (244.3 cm 2 ) n-type Cz, with a potential efficiency above 24%. Some of these co-plated bifacial cells have been processed into one-cell laminates using smart wire interconnection (SWCT) technology. These have passed thermal cycling (TC) tests as defined in IEC61215.

TOPerc Solar Cell: An Integral Approach of Tunnel Oxide Passivated Contact (TOPCon) and Passivated Emitter and Rear Contact (PERC) Architectures for Achieving Efficiency Beyond 25%

“…Step 2: Now this 17 μm  17 μm device (Figure 3b) is scaled by 100 along Y-axis and also scaled by 100 along X-axis which is the [10][11][12] unit cell (Figure 3a). During scaling, each layer is considered by "entity list."…”

“…After that the rear side is masked with stearic acid, [ 10 ] antiacid paste, [ 11 ] and thick oxide layer using UV laser. [ 12 ] The uncovered poly‐Si regions on rear side may be etched by KOH solution [ 10 ] or HF/HNO 3 solution [ 11 ] or TMAH [ 12 ] using a single‐side etcher after that masks are removed. Then the front side is masked with stearic acid, [ 10 ] antiacid paste, [ 11 ] and thick oxide layer using UV laser.…”

“…There are very few literatures where they have fabricated p-PERC and n-TOPCon with passivated front contact but not achieved substantial performance. [10][11][12] Yuan et al fabricated p-PERC with passivated front contacts and achieved an efficiency of 22.6% on a large area mono CZ wafer. [10] However, for further improvement of efficiency the rear contacts also may be passivated (Figure 1c).…”

Silicon solar cells with passivating contacts: Classification and performance

“…More details on the intricacies of each of these passivating contact technologies is discussed extensively in other articles within this special issue on passivating contacts based silicon solar cells. For example, Zhao et al present strategies to improve the performance of SHJ solar cells 12 ; Glunz et al present an overview of the historical development of poly‐Si passivating contacts and their current status in both industry and research laboratories 5 ; Singh et al and Nandakumar et al focus on the industrial aspects of poly‐Si passivating contacts, 13,14 ; and Ibarra Michel et al review metal compound‐based passivating contacts 15…”

“…Finally, in a third family (Section 4) we group all the contact/junction systems that, rather than employing doped silicon films, utilize the on the industrial aspects of poly-Si passivating contacts, 13,14 ; and Ibarra Michel et al review metal compound-based passivating contacts. 15 Each efficiency table is composed of three parts.…”