Review and Understanding of Screen-Printed Contacts and Selective--Emitter Formation. Preprint.

Hilali, M. M. ; Rohatgi, A. ; To, B.

Technical Information Center Oak Ridge Tennessee

关键词: Solar cells;    Screen printing;    Back contact cells;    Photolithography;    Glass frits;   

RP-ID  :  DE200415009892

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

A comparison of the loss mechanisms in screen-printed solar cells relative to buried contact cells and cells with photolithography-defined contacts is presented in this paper. Model calculations show that emitter recombination accounts for about 0.5% absolute efficiency loss in conventional screen-printed cells with low-sheet-resistance emitters. Ohmic contact to highsheet- resistance emitters by screen-printing has been investigated to regain this efficiency loss. Our work shows that good quality ohmic contacts to high sheet-resistance emitters can be achieved if the glass frit chemistry and Ag particle size are carefully tailored. The melting characteristics of the glass frit determine the firing scheme suitable for low contact resistance and high fill factors. In addition, small to regular Ag particles were found to help achieve a higher open-circuit voltage and maintain a low contact resistance. This work has resulted in cells with high fill factors (0.782) on high sheet-resistance emitters and efficiencies of 17.4% on planar float zone Si substrates, without the need for a selective emitter.