A 12%-Efficient Upgraded Metallurgical Grade Silicon鈥揙rganic Heterojunction Solar Cell Achieved by a Self-Purifying Process
详细信息 查看全文
- 作者：Jie Zhang ; Tao Song ; Xinlei Shen ; Xuegong Yu ; Shuit-Tong Lee ; Baoquan Sun
- 刊名：ACS Nano
- 出版年：2014
- 出版时间：November 25, 2014
- 年：2014
- 卷：8
- 期：11
- 页码：11369-11376
- 全文大小：496K
- ISSN：1936-086X
文摘
Low-quality silicon such as upgraded metallurgical-grade (UMG) silicon promises to reduce the material requirements for high-performance cost-effective photovoltaics. So far, however, UMG silicon currently exhibits the short diffusion length and serious charge recombination associated with high impurity levels, which hinders the performance of solar cells. Here, we used a metal-assisted chemical etching (MACE) method to partially upgrade the UMG silicon surface. The silicon was etched into a nanostructured one by the MACE process, associated with removing impurities on the surface. Meanwhile, nanostructured forms of UMG silicon can benefit improved light harvesting with thin substrates, which can relax the requirement of material purity for high photovoltaic performance. In order to suppress the large surface recombination due to increased surface area of nanostructured UMG silicon, a post chemical treatment was used to decrease the surface area. A solution-processed conjugated polymer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was deposited on UMG silicon at low temperature (<150 掳C) to form a heterojunction to avoid any impurity diffusion in the silicon substrate. By optimizing the thickness of silicon and suppressing the charge recombination at the interface between thin UMG silicon/PEDOT:PSS, we are able to achieve 12.0%-efficient organic鈥搃norganic hybrid solar cells, which are higher than analogous UMG silicon devices. We show that the modified UMG silicon surface can increase the minority carrier lifetime because of reduced impurity and surface area. Our results suggest a design rule for an efficient silicon solar cell with low-quality silicon absorbers.