Abstract
AbstractPoly(3,4‐ethylenedioxy thiophene):poly(styrenesulfonate) (PEDOT:PSS) exhibits valuable characteristics concerning stability, green‐processing, flexibility, high electrical conductivity, and ease of property modulation, qualifying it as one of the most promising p‐type organic conductors for thermoelectric (TE) applications. While blending with inorganic counterparts is considered a good strategy to further improve polymeric TE properties, only a few attempts succeed so far due to inhomogeneous embedding and the non‐ideal organic‐inorganic contact. Here a new strategy to include nanoparticles (NPs) without any ligand termination inside PEDOT:PSS thin films is proposed. Spark discharge‐generated tin oxide NPs (SnOx‐NPs) are “gently” and homogenously deposited through low‐energy diffusion mode. Strong interaction between naked SnOx‐NPs and PSS chains occurs in the topmost layer, causing a structural reorganization towards an improved PEDOT chains crystalline packing at the bottom, providing a positive contribution to the electrical conductivity. Meanwhile, dedoping and energy filtering effect introduced by the SnOx‐NPs cause dramatic Seebeck coefficient enhancement. The optimized power factor of 116 μWm−1 K−2 achieved is more than six times higher than the value found for the film without NPs. This easy and efficient strategy promises well for future mass production of flexible TE devices and the mechanism revealed may inspire future research on TEs and flexible electronics.
Highlights
The NPs were widely and homogeneously dispersed on the Cu grid, which is very important for the preparation of homogeneous hybrid films with PEDOT:PSS
This value is further confirmed by scanning electron microscopy (SEM) and grazing incidence small-angle X-ray scattering (GISAXS) as shown in Figure S1, Supporting Information
The grazing incidence wide-angle X-ray scattering (GIWAXS) pattern exhibits a sharp peak located at q = 1.85 Å−1 suggesting a d-spacing of 3.4 Å, which can be attributed to the (110) plane of SnO2.[18]. Oxidation of the NPs is expected in our case due to the exposure to air
Summary
It can be clearly observed that there is a layer with higher electron density on the top region, the composition of which should be an enriched PSS phase (as verified by XPS) containing the SnOx NPs. Compared with PEDOT:PSS:DMSO film, the hybrid system shows a different electron density distribution at the film/air interface region, which indicates a restructuring of the film surface (even smoother) in line with our AFM observation.[34] Besides, the lower electron density at the bottom part suggests that PSS migration on the top region of the film induces formation of a bottom region with more densely packed PEDOT crystallites, resulting in a more coherent carrier charge transport path.
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