Open AccessPhotoexcited Carrier Dynamics of Cu2S Thin Films
Author(s) -
Shan C. Riha,
Richard D. Schaller,
David J. Gosztola,
Gary P. Wiederrecht,
Alex B. F. Martinson
Publication year - 2014
Publication title -
the journal of physical chemistry letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.563
H-Index - 203
ISSN - 1948-7185
DOI - 10.1021/jz5021873
Subject(s) - thin film , photovoltaics , passivation , grain boundary , materials science , solar cell , cadmium sulfide , copper sulfide , grain size , czts , analytical chemistry (journal) , layer (electronics) , copper , optoelectronics , chemical engineering , chemistry , nanotechnology , photovoltaic system , metallurgy , microstructure , ecology , engineering , biology , chromatography
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 μs. 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.
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