Screen-printable Material and Process Solutions for High-efficiency Crystalline Silicon Solar Cells

摘要

In this paper, we will describe three kinds of screen-printable materials, that is, n/p-type doping pastes, surface passivation paste and Cu-alloy electrode paste. The n/p-type doping pastes have three main features: (ⅰ) uniform and controllable sheet resistance, (ⅱ) minimal out-diffusion, and (ⅲ) no residue. These can be applicable to high-efficiency solar cells such as selective emitter, back contact and bi-facial structure. The surface passivation paste has also three main features: (ⅰ) easy to form thin-layer patterning by screen printing, (ⅱ) field-effect passivation, and (ⅲ) comparable negative fixed charge density to ALD-Al_2O_3. Therefore, this can be alternative to ALD or PECVD passivation for fabricating the local back-surface-field cell in a lower-cost process. The Cu-alloy electrode paste is the replacement to reduce material cost of the Ag-paste. This paste is composed of Cu-alloy, glass frit, solvent and binder. By firing at around 800 °C, the barrier layer is formed outside of the conductive layer (Cu-alloy) and prevents Cu-migration to Si. These screen-printable materials enable to provide high-efficiency crystalline silicon solar cell without significant additional process and cost.