Novel paths towards next generation heterojunction solar cell and module

Heterojunction solar cells represent the solar module technology of the future. The challenge today is linked to the fact that the cells cannot withstand temperatures higher than 200 degrees Celsius. This means that today's metallization and interconnection technology becomes disproportionately expensive due to the need for much more silver than is traditionally used. In this project, we will look at copper as an alternative material for the metal contacts on the cell, to dramatically reduce the Ag consumption. The interconnection of the cells will be done with the help of Conpart's SphericaTM technology, that is conductive glue with a very low silver content, . A main activity in the project will be to provide good electrical contact to the TCO layer and the copper metallization which is exposed to oxidation. In collaboration with Henkel, we will develop adhesives based on our Spherica technology. Optimization of particle properties to minimize the silver content and at the same time provide the necessary conductivity. Together with IFE, we will assemble mini-modules and investigate performance, reliability and potential failure mechanisms.

Currently, SHJ solar cell metallization utilizes screen printing of low-temperature sintering paste with high Ag content (>90%), resulting in high Ag consumption and production costs. To address this challenge, Cu is proposed as an alternative material for metal contact to reduce Ag consumption. Low-temperature interconnection processes (below 200 °C) are essential for the fabrication of SHJ solar modules to prevent surface passivation deterioration. Interconnecting the cells with electrically conductive adhesive (ECA) with ultra-low silver consumption (Spherica (TM) technology) has a great potential for this application. The ECA combines low assembly temperature with high mechanical flexibility. A main activity in the project will be to provide good electrical contact to the TCO layer and the copper metallization that is prone to oxidize. In collaboration with Henkel we will develop adhesives based on our Spherica technology. Optimization of particle properties to minimize silver content while still providing required conductivity. Together with IFE we will assemble mini-modules and investigate performance, reliability and potential failure mechanisms.