Ethanedithiol Treatment of Solution-Processed ZnO Thin Films: Controlling the Intragap States of Electron Transporting Interlayers for Efficient and Stable Inverted Organic Photovoltaics
2015 (English)In: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 5, no 5, 1401606- p.Article in journal (Refereed) Published
The surface defects of solution-processed ZnO films lead to various intragap states. When the solution-processed ZnO films are used as electron transport interlayers (ETLs) in inverted organic solar cells, the intragap states act as interfacial recombination centers for photogenerated charges and thereby degrade the device performance. Here, a simple passivation method based on ethanedithiol (EDT) treatment is demonstrated, which effectively removes the surface defects of the ZnO nanocrystal films by forming zinc ethanedithiolates. The passivation by EDT treatment modulates the intragap states of the ZnO films and introduces a new intragap band. When the EDT-treated ZnO nanocrystal films are used as ETLs in inverted organic solar cells, both the power conversion efficiency and stability of the devices are improved. The control studies show that the solar cells with EDT-treated ZnO films exhibit reduced charge recombination rates and enhanced charge extraction properties. These features are consistent with the fact that the modulation of the intragap states results in reduction of interfacial recombination as well as the improved charge selectivity and electron transport properties of the ETLs. It is further demonstrated that the EDT treatment-based passivation method can be extended to ZnO films deposited from sol-gel precursors.
Place, publisher, year, edition, pages
Wiley-VCH Verlag , 2015. Vol. 5, no 5, 1401606- p.
electron transporting interlayers; intragap states; molecular passivation; organic solar cells; ZnO thin films
IdentifiersURN: urn:nbn:se:liu:diva-116817DOI: 10.1002/aenm.201401606ISI: 000350754800013OAI: oai:DiVA.org:liu-116817DiVA: diva2:800761
Funding Agencies|National High Technology Research and Development Program of China [2011AA050520]; National Basic Research Program of China (973 Program) [2012CB932402]; National Natural Science Foundation of China ; Natural Science Funds for Distinguished Young Scholar of Zhejiang Province [R4110189]; Public Welfare Project of Zhejiang Province [2013C31057]; Swedish Energy Agency (Energimyndigheten); Swedish Research Council (VR); European Commission under a Marie Curie Intra-European Fellowship for Career Development2015-04-072015-04-072015-06-03