荷兰代尔夫特理工大学成功降低非晶硅太阳能电池光劣化现象

　　荷兰代尔夫特理工大学（Delft University of Technology）宣布，该大学的研究人员成功地大幅减低了非晶硅型太阳能电池转换效率的光劣化现象。即使针对以前转换效率在制造完成后为10％、稳定后降至7％左右的情况，也可将稳定后的数值维持在9％。

　　这一结果是该大学电机工程系数学与计算机科学专业（Faculty of Electrical Engineering, Mathematics and Computer Science）的学生Gijs van Elzakker在博士论文中发布的。非晶硅型太阳能电池此前一直存在Staebler-Wronski效应现象，当被强光照射时转换效率会大幅下降。

　　Elzakker发现，当以硅烷（SiH4）和氢气的混合气体为基础形成非晶硅层时，通过控制氢气的浓度，可以大幅减轻上述光劣化问题。

　　该项技术已被用于德国太阳能电池厂商Inventux Technologies AG的生产线中。Elzakker已决定到该公司工作。

TU Delft raises energy yield of cheap solar panels

Researchers from TU Delft have shown how the energy yield of relatively cheap solar panels, made of amorphous silicon, can be considerably raised: from around 7 percent to 9 percent. Gijs van Elzakker will obtain his PhD on this subject from TU Delft on Tuesday 6 July.

(Photo: thin film silicon solar cells on a building in Germany.
Courtesy of: Inventux Technologies AG)

Amorphous
Researcher Gijs van Elzakker focused on solar panels that are made from so-called amorphous silicon, as opposed to the more commonly used crystalline silicon. Amorphous silicon has the great advantage that the solar panels can be produced relatively cheaply using a very thin layer of silicon (thin film solar cells).

Yield
The major disadvantage of solar panels made with amorphous silicon is that their yield is relatively low. While crystalline silicon achieves a yield of around 18 percent, amorphous silicon, until recently, remained at around 7 percent. This is partly because the amorphous silicon panels suffer from the so-called Staebler-Wronski effect. This phenomenon, which has still not been fully explained by science, manifests itself in the first hours that the panels are exposed to sunlight. Because of this the yield falls by around a third, from around 10 percent to around 7 percent.

(Photo: thin film silicon solar cells on a building in Germany.
Courtesy of: Inventux Technologies AG)

Silane
In his doctoral research Gijs van Elzakker investigated adaptations in the production process that could raise the yield. The silicon layer in the solar panels he studied is made of silane gas (SiH4). The structure of the silicon layer can be changed by diluting this silane gas with hydrogen during the production process. The use of hydrogen appears to enable the reduction of the negative Staebler-Wronski effect.

Hydrogen
Van Elzakker concentrated, among other factors, on the proportion of hydrogen to silane gas. He determined the optimum ratio of hydrogen to silane in the production process. Van Elzakker: "We showed that the influence of the Staebler-Wronski effect can be considerably reduced in this way. If this knowledge is applied in the manufacture of this type of solar cells, a yield of 9 per cent can be expected."

Gijs van Elzakker's findings are already being applied on the production line of the German company Inventux Technologies, where he now works.

More information:
Gijs van Elzakker, Photovoltaic Materials and Devices, Faculty of Electrical Engineering, Mathematics and Computer Science, TU Delft. Tel: +49 (0)30 92377309 or +31 (0)70 7113584, e-mail: gijs@vanelzakker.nl.

Ineke Boneschansker, Science Information Officer, TU Delft. Tel: +31 (0)15 278 8499, e-mail: i.boneschansker@tudelft.nl.