Photoexcited Carrier Dynamics of Cu2S Thin Films

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• 作者：Shannon C. Riha ; Richard D. Schaller ; David J. Gosztola ; Gary P. Wiederrecht ; Alex B. F. Martinson
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2014
• 出版时间：November 20, 2014
• 年：2014
• 卷：5
• 期：22
• 页码：4055-4061
• 全文大小：366K
• ISSN：1948-7185

文摘

Copper sulfide is a simple binary material with promising attributes for low-cost thin film photovoltaics. However, stable Cu₂S-based device efficiencies approaching 10% free from cadmium have yet to be realized. In this Letter, transient absorption spectroscopy is used to investigate the dynamics of the photoexcited state of isolated Cu₂S thin films prepared by atomic layer deposition or vapor-based cation exchange of ZnS. While a number of variables including film thickness, carrier concentration, surface oxidation, and grain boundary passivation were examined, grain structure alone was found to correlate with longer lifetimes. A map of excited state dynamics is deduced from the spectral evolution from 300 fs to 300 渭s. Revealing the effects of grain morphology on the photophysical properties of Cu₂S is a crucial step toward reaching high efficiencies in operationally stable Cu₂S thin film photovoltaics.

Keywords:

Cu₂S thin films; photovoltaics; thin film solar cell; transient absorption spectroscopy; atomic layer deposition; photophysical properties