In Situ Solar Wafer Temperature Measurement during Firing Process via Inline IR Thermography

Herein, an inline IR thermography system as an innovative application for real‐time contactless temperature measurement of wafers—both metallized and nonmetallized-during the firing process is successfully realized in an industrial firing furnace as proof of concept and example for a thermography system in a conveyor furnace. As observed by the new system, thermocouples (TCs) seem to measure lower temperature on wafers-especially in combination with TC frames-than wafers exhibit at standard firing conditions (here up to ΔT ≈ 40 K). Furthermore, highly resolved spatial temperature distribution can be successfully measured on the wafer

Optimization of Rear Side Al Fire-Through Contacts for AlOx-SiNx Rear Passivated Bifacial Cz p-PERC cells: Presentation held at 36th European Photovoltaic Solar Energy Conference and Exhibition 2019, Marseille, France, 09-13 September 2019

While standard monofacial p-type passivated emitter and rear cells (PERC) require laser contact opening (LCO) of the rear side (RS) passivation layers, bifacial (bifi) PERC allow for application of RS Al fire-through contact (FTC) fingers that etch through the RS passivation layers during the contact firing step [1] with the help of the added glass frit. Hence the bifi PERC process chain can be skipped by the relatively demanding laser step, making the further growth of bifi PERC in market share [2] more promising. So far, successful RS passivation layer etching and subsequent back surface field (BSF) formation have been achieved with FTC for various RS passivation types [1, 3, 4]. However, for AlOX/SiNX passivation - the PERC RS passivation type with the highest market share [2] – BSF formation has not been successful yet. Combined with generally higher contact area for FTC, the missing BSF leads to higher recombination, compared to the non-FTC (NFTC) bifi PERC approach. Therefore the aim of this work is to reduce the recombination of FTC to the level of NFTC and thus optimizing Al-FTC bifi p-type PERC with RS AlOX/SiNX passivation

Large Area TOPCon Cells Realized by a PECVD Tube Process

TOPCon is an appealing choice for next-generation solar cells as it minimizes surface recombination, enables low contact resistivities, and provides high thermal stability thereby rendering it compatible with screen-printed metallization. While TOPCon is commonly realized by low-pressure chemical vapor deposition (LPCVD), this paper discusses the use of a plasma-enhanced chemical vapor deposition (PECVD) tool, which are commonly used for deposition of SiNx or AlOx. It will be shown that thick screen-printing compatible TOPCon layers providing excellent surface passivation can be realized with such tool. Additionally, the firing stability of TOPCon/SiNx stack will be discussed and first solar cell results will be presented. The IV parameters of the best solar cell were: Voc = 691.2 mV, FF = 80.7%, Jsc = 40.4 mA/cm², and = 22.5%