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Published on: October 28, 2025
Electric and Photoelectric Properties of 3,4-Ethylenedioxythiophene-Functionalized n-Si/PEDOT:PSS Junctions
Patrick K Giesbrecht1, Jared P Bruce1,2, Michael S Freund3,4
1Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada.
Abstract:
Organic/inorganic solid-state junctions play a critical role in tandem artificial photosynthetic devices supported by conducting polymer membranes. Recent work with n-Si/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (
Pedot:
PSS) hybrid junctions has shown that the electrical behavior is dominated by the passivating groups present on the silicon surface. In this work, the photovoltaic behavior of n-Si/
Pedot:
PSS was investigated with methyl, thiophene, and 3,4-ethylenedioxythiophene (EDOT) groups covalently attached to the Si(111) surface. X-ray photoelectron spectroscopy results demonstrated that complete monolayer coverage was achieved in 3 h and that the organic passivating groups were retained over two months of exposure to ambient conditions with minimal silicon oxidation. All surfaces investigated exhibited similar light-limited photocurrents and bulk-limited open-circuit voltages, and thiophene produced a dramatic reduction of the fill factor attributed to the formation of trap states at the interface. Furthermore, shunt behavior observed near the power-producing regions for the thiophene and EDOT surfaces is indicative of increased recombination events under forward bias and suggests that hole transport across the interface is enhanced. Thus, thiophene- and EDOT-functionalized Si(111) offer similar stabilities and efficiencies to those of methylated surfaces as well as enhanced hole transport to the
Pedot:
PSS interface from the n-Si surfaces.
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