Development of high-efficiency large-area screen-printed solar cells on direct kerfless epitaxially grown monocrystalline Si wafer and structure

作者：Chen Chia Wei^*; Hao Ruiying; Upadhyaya Vijaykumar D; Ravi T S; Rohatgi Ajeet

来源：Progress in Photovoltaics: Research and Applications , 2016, 24(8): 1133-1141.

DOI：10.1002/pip.2779

• p-type wafer
• kerfless wafer
• PERC
• PERT
• epi-Si
• layer transfer
• In situ BSF

This paper demonstrates the potential of epitaxially grown Si wafers with doped layers for high-efficiency solar cells. Boron-doped 239cm(2) 180-200 mu m thick 2-cm wafers were grown with and without 15 mu m thick p(+) layer, with a doping in the range of 10(17 similar to)10(18)cm(-3). A layer transfer process involving porous Si layer to lift off epi-Si wafers from the reusable substrate was used. The pp(+) wafers were converted into n(+)pp(+) passivated emitter rear totally diffused (PERT) cells by forming an oxide-passivated POCl3-diffused n(+) emitter at the front, and oxide/nitride-passivated epitaxially grown p(+) BSF at the entire back, with local screen-printed contacts. To demonstrate and quantify the benefit of the epi-grown p(+) layer, standard passivated emitter and rear cells (PERCs) with local BSF and contacts were also fabricated on p-type epi-Si wafers as well on commercial-grade Cz wafers. Sentaurus 2D device model was used to assess the impact of the epi-grown p(+) layer, which showed an efficiency gain of similar to 0.5% for this PERT structure over the traditional PERC. This was validated by the cell results, which showed an efficiency of similar to 20.1% for the PERC, and similar to 20.3% for the PERT cell using epi-Si wafers. Experimental data showed higher FF in PERT cells, largely because of the decrease in lateral resistance on the rear side. Efficiency gain, a result of higher FF, was greater than the recombination loss in the p(+) layer because of the lightly doped thick p(+) epi-grown region used in this study.

• 出版日期2016-8