Unveiling the Hybrid n-Si/PEDOT:PSS Interface

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• 作者：Sara Jäckle ; Martin Liebhaber ; Jens Niederhausen ; Matthias Büchele ; Roberto Félix ; Regan G. Wilks ; Marcus Bär ; Klaus Lips ; Silke Christiansen
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：April 6, 2016
• 年：2016
• 卷：8
• 期：13
• 页码：8841-8848
• 全文大小：429K
• ISSN：1944-8252

文摘

We investigated the buried interface between monocrystalline n-type silicon (n-Si) and the highly conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), which is successfully applied as a hole selective contact in hybrid solar cells. We show that a post-treatment of the polymer films by immersion in a suitable solvent reduces the layer thickness by removal of excess material. We prove that this post-treatment does not affect the functionality of the hybrid solar cells. Through the thin layer we are probing the chemical structure at the n-Si/PEDOT:PSS interface with synchrotron-based hard X-ray photoelectron spectroscopy (HAXPES). From the HAXPES data we conclude that the Si substrate of a freshly prepared hybrid solar cell is already oxidized immediately after preparation. Moreover, we show that even when storing the sample in inert gas such as, e.g., nitrogen the n-Si/SiO_x/PEDOT:PSS interface continues to further oxidize. Thus, without further surface treatment, an unstable Si suboxide will always be present at the hybrid interface.