One-step post-treatment boosts thermoelectric properties of PEDOT:PSS flexible thin films

Developing high-performance poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)sig-nificantly widens the practical applications of flexible organic thermoelectric devices,while the water-based co-solvent dopants and/or post-treatments are still rarely studied so far.Here,we develop a one-step post-treatment to improve the power factor of PEDOT:PSS films by using a water-based solution,which is composed of co-solvent(polar solvent dimethylacetamide(DMAC)and deionized water)and organic reducing agent L-ascorbic acid(LAA).The 80 vol.%DMAC solution significantly boosts the room-temperature electrical conductivity of the films from 5 to 964 S cm^(−1),while the Seebeck coefficient can be further enhanced from 18.7 to 25μV K−1 by treating with 0.5 mol L−1 LAA,contributing to a sig-nificantly improved power factor of 55.3μW m^(−1)K^(−2).The boosted electrical conductivity is ascribed to the separated PEDOT and PSS phases triggered by the high dielectric constant and polarity of DMAC;while the improved Seebeck coefficient is attributed to the reduced oxidation degree of PEDOT from the reducing agent LAA,both confirmed by the comprehensive structural and morphological characteri-zations.Furthermore,a maximum power factor of 64.4μW m^(−1)K^(−2)can be achieved at 360 K and the observed temperature-dependent electrical transport behavior can be well explained by the Mott variable range hopping model.Besides,a flexible thermoelectric device,assembled by the as-fabricated PEDOT:PSS films,exhibits a maximum output power of∼23 nW at a temperature difference of 25 K,indicating the potential for applying to low-grade wearable electronics.

Preliminary studies on the cryopreservation of spermatozoa in the fresh water fish common carp(Cyprinus carpio L.)

Objective:To investigate the effects of various extenders containing different cryoprotectants on post-thaw viability,motility and scanning electron microscopic study of frozen spermatozoa from carp.Methods:cryopreservation has been achieved using extender and cryoprotectants like dimethylacetamide After screening a variety of cryoprotectants and extenders,a protocol for the 5%-20%at appropriate dilution ratio(1:10).For all experimental tests,the motility and viability percentage of spermatozoa were examined after storage of 5 d at 4℃.Results:The maximum motility of 75%has been observed with 10%dimethyl sulfoxide.Scanning electron microscopic studies on normal and cryopreserved spermatozoa showed prominent head,middle piece and different segments of flagellum.There were no significant deformities noticed on the surface topography of cryopreserved spermatozoa.Conclusions:Thus the results clearly documented that cryoprotectant 10%dimethyl sulfoxide affords better cryopreservation at 4℃for the spermatozoa of Cyprinus carpio.