Jul 3, 2013
Silicon nanowire based large-scale solar cells receive upgrade
Suppression of carrier recombination in silicon nanowires (SiNWs) is a key area for improving the performance of SiNW-based solar cells. Reporting their results in the journal Nanotechnology, researchers from Shanghai Jiao Tong University, China, have employed efficient dielectric passivation technology to realize high-performance SiNW based solar cells with a conversion efficiency of 17.11% and a large size of 125 × 125 mm2.
The team has demonstrated that a SiO2/SiNx stack can provide a good passivation effect on electrical properties upon heavily doped SiNWs, reducing both the Shockley-Read-Hall recombination and near surface Auger recombination, while maintaining the excellent anti-reflection and light-trapping effects of these structures.
"We have degraded the recombination rate at and near the surface to 20% in SiO2/SiNx stack passivated SiNW based solar cells compared with bare SiNW cells,” X X Lin told nanotechweb.org.
What’s more, the efficiency of the SiNW based solar cells can be further improved with a carefully designed diffusion process, in order to minimize the unfavorable Auger recombination near the surface.
"The sheet resistance of our samples after diffusion is around 75 Ω/sq," commented X Hua. "In the next stage of our work we would like to increase the sheet resistance to higher than 125–150 Ω/sq."
W Z Shen, who leads the team, explains that the group is improving the cell performance by introducing a selective emitter structure and selective growth of SiNWs in the active area for better front electrical contact.
Full details can be found in the journal Nanotechnology.
About the author
The work was carried out at Shanghai Jiao Tong University, Shanghai, China, by Prof. W Z Shen and his research team, Ms X X Lin, Mr X Hua, and Mr Z G Huang. Dr W Z Shen is National Cheung Kong chair professor of condensed matter physics at Shanghai Jiao Tong University, China, and winner of National Science Foundation for Distinguished Young Scholars. Prof. W Z Shen is the director of the Institute of Solar Energy and Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education). This work was supported by the National Major Basic Research Projects (2012CB934302 and 2011AA050518) and the Natural Science Foundation of China (11074169, 11174202, and 61234005).