Application of SunsPL for fast laser chemical process development

Glatthaar, Markus; Kray, D.; Bay, N.; Burschik, J.; Cimiotti, G.; Fritz, Nathan; Kleinschmidt, Sebastian; Kühnlein, H.; Lösel, A.; Lühn, Ole; Nussbaumer, Hartmut; Rodofili, A.; Sastrawan, R.; Sieber, M.; Schramm-Moura, J.; Träger, Andrea

doi:10.1109/pvsc.2011.6186544

Cited by 3 publications

(1 citation statement)

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“…The images before and after the laser process were carefully aligned. A map of the V OC ‐loss was generated by calculating the change of the implied V OC for each pixel :

Δ V_{O C, x y} = V_{normalT} \ln true(\frac{n_{normalb normale normalf normalo normalr normale, normalx normaly}}{n_{normala normalf normalt normale normalr, normalx normaly}} true)

with the thermal voltage V T and the PL count rates before and after the process counted in camera pixel xy: n before,xy and n after,xy . The V OC ‐loss of each individual field corresponding to one set of laser parameters was calculated by averaging over the field.…”

Section: Parameters (Measured Under Stc) Of Two Identically Procesmentioning

confidence: 99%

Laser Transfer and Firing of NiV Seed Layer for the Metallization of Silicon Heterojunction Solar Cells by Cu-Plating

et al. 2017

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We present a laser-based method for the metallization of silicon heterojunction solar cells by Cu-plating. It consists of first applying a dielectric layer on the transparent conductive oxide (TCO) as a plating mask. Then, a NiV seed is transferred by laser induced forward transfer (LIFT) from a plastic carrier foil onto the wafer. In the second laser step, the NiV layer is fired through the dielectric layer to form a contact to the TCO. After the laser process, Cu-fingers are produced by plating. The dielectric plating mask remains on the cell. Parasitic plating is prevented by using an advanced reverse pulse plating process. With the first solar cells we reach a maximum efficiency of 22.2% and an efficiency gain of 0.5% abs compared to lowtemperature screen printing reference cells, due to a higher short circuit current and fill factor. The 30 mm wide fingers reach specific contact resistances down to 0.6 mV cm 2 and also, pass a tape adhesion test. We further demonstrate that the laser process does not cause any measurable open circuit voltage loss and that a precise alignment of the two laser steps is not necessary.Silicon heterojunction (SHJ) solar cells are believed to play a major role in the future PV market [1] . Compared to homojunction solar cells, they offer a superior module performance due to their higher open circuit voltage and their lower temperature coefficient. Moreover, the production is relatively simple and does not require high temperature steps. However, a drawback for this technology still is the metallization. Screen printed metallization can only be applied with special expensive low temperature silver pastes [2] , because the passivation by the amorphous silicon (a-Si) layers of SHJ cells cannot withstand temperatures above 200-250 C [3] . Lowtemperature silver pastes reach resistivities between 5 and 10 mVcm [4] , which is far higher than for standard silver pastes sintered at high temperature (>800 C). The typical width of industrially produced screen printed fingers on SHJ cells lies between 60 and 80 mm.Cu-plating as a low temperature metallization is a more suitable technology. Kaneka has recently presented a plated SHJ solar cell with 25.1% efficiency, which represents the world record for both-sidecontacted SHJ solar cells [5] . Depending on the masking approach, plated fingers can be much thinner than screen printed fingers and the resistivity of plated metal is very close to that of bulk Cu (1.7 mVcm). In fact, plating has shown to outperform low temperature screen printing due to a higher fill factor (FF) [6] and a higher short circuit current (J SC ) [7] . High peel forces (3-5 N/mm) for plated copper fingers on TCO have been measured with an intermediate seed layer [8,9] . In addition, plating imposes less mechanical stress onto the wafer than screen printing, which is an advantage in view of thinner wafers expected in the future [1] .In order to plate a grid structure on the TCO surface of SHJ cells, in most cases, a structured organic plating mask is applied, which covers...

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“…The images before and after the laser process were carefully aligned. A map of the V OC ‐loss was generated by calculating the change of the implied V OC for each pixel :