Study of Various Screen-Printed Pastes for Single- and Multi-crystalline Silicon Solar Cells Applications

Abstract

A typical silicon solar cell consists of a p-n junction formed on the surface a front ohmic contact stripe and fingers a back contact that covers the entire back surface and an antireflection coating on the front surface Screen-printed solar cells are the most widely used cells in the commercial production of silicon solar cells The key advantage of screen printing is the relative simplicity of the process in spite of its high contact resistance and high shading loss Commercial mono- and multi-crystalline silicon solar cells use screen-printed process for depositing both the front and rear Ag paste based gridded electrodes and Al based back whole area metal contacts Conductive paste usually consists of four constituents: silver or aluminum powder organic vehicle glass frit and additive To date there have many researchers dedicating to improve the performance of screen-printed front contacts for mono- and multi-crystalline silicon solar cells This thesis placed more emphasis on the study of the effects of glass frit recipe silver powder size and temperature on properties The experimental results show that the welding tension of the front-side electrodes printed by small size silver particle is bigger than that of the front-side electrodes printed by big size silver particles that is to say the front-side silver electrode printed by silver paste made of small size silver powder contact very closely with the silicon wafer and have the best welding performance The rear-side electrode of silver paste prepared by low Tg glass frit has the largest welding tension and the welding tension of each electrode is uniform The Al paste/Al-Si eutectic layer/Al-P+ layer (Back-Surface-Field BSF)/Si(100) stacked structure was obtained by firing the Al paste/Si(100) stacked substrate A BSF layer can be formed by the regrown silicon due to large amount of Si dissolved in the Al melt The glass frit layer was formed between the porous Al bulk and the silicon substrate interface after finished contact Thus it was difficult to incorporate the Al particles into the silicon substrate through higher Tg of glass frit when the stacked Al paste/Si(100) structure was co-fired at 780 oC To achieve novel cooling technology for solar module the performance of screen-printed SiC paste on the back side of solar cell was added Since SiC has good thermal radiation function thus its application on PV module can effectively enhance the heat flow from solar cell to back sheet thus increases generation of electricity

Date of Award	2015 Aug 28
Original language	English
Supervisor	Thou-Jen Whang (Supervisor)