Preparation and Characterization of Screen-Printed Cu2S/PEDOT:PSS Hybrid Films for Flexible Thermoelectric Power Generator

Abstract

In recent years, flexible thermoelectric generators(f-TEG), which can generate electricity by environmental temperature difference and have low cost, have been widely concerned in self-powered energy devices for underground pipe network monitoring. This paper studied the Cu2S films by screen-printing. The effects of different proportions of p-type Cu2S/poly 3,4-ethylene dioxythiophene-polystyrene sulfonate (PEDOT:PSS) mixture on the thermoelectric properties of films were studied. The interfacial effect of the two materials, forming a superconducting layer on the surface of Cu2S, leads to the enhancement of film conductivity with the increase of PEDOT:PSS. In addition, the Seebeck coefficient decreases with the increase of PEDOT:PSS due to the excessive bandgap difference between the two materials. When the content ratio of Cu2S and PEDOT:PSS was 1:1.2, the prepared film had the optimal thermoelectric performance, with a maximum power factor (PF) of 20.60 μW·m−1·K−1. The conductivity reached 75% of the initial value after 1500 bending tests. In addition, a fully printed Te-free f-TEG with a fan-shaped structure by Cu2S and Ag2Se was constructed. When the temperature difference (ΔT) was 35 K, the output voltage of the f-TEG was 33.50 mV, and the maximum power was 163.20 nW. Thus, it is envisaged that large thermoelectric output can be obtained by building a multi-layer stacking f-TEG for continuous self-powered monitoring.

Greatly Enhanced Thermoelectric Performance of Flexible Cu2−xS Composite Film on Nylon by Se Doping

“…Owing to enhanced σ (69.4 S cm −1 ) and high α (147.0 μV K −1 ), the Cu2−xS0.98Se0.02 film exhibits a maximum PF of 150.1 μW m −1 K −2 at RT, which is ~138% higher than that of the undoped Cu2−xS film. The PF increases to 244.5 μW m −1 K −2 at 403 K. Figure 4f shows a comparison of the PF values at RT of our work and reported Cu2S-based bulks [25,26,29,43] and flexible films [30,44,45]. The present PF value is outstanding compared to that of the reported Cu2S-based flexible films and comparable with that of Cu2S1−xSex bulk (PF = 115.2 μW m −1 K −2 ) [26].…”

“… TE parameters of the Cu 2−x S 1−y Se y (y = 0,0.01,0.02,0.03) films: ( a ) temperature dependence of σ, ( b ) plot of ln ρ vs. 1/T, ( c ) temperature dependence of α , ( d ) temperature dependence of n and μ for the Cu 2−x S 0.98 Se 0.02 film, ( e ) temperature dependence of PF, ( f ) comparison of PF between this work and other reported Cu 2 S-based bulks [ 25 , 26 , 29 , 43 ] and flexible films [ 30 , 44 , 45 ] at room temperature. …”

“…Cracks are generated at pores and fewer pores contribute to the better flexibility. Compared to the σ / σ 0 results of reported Cu 2 X (X = S, Se) films [ 30 , 44 , 45 , 46 ] and other films (Bi 2 Te 3 [ 14 ], Ag 2 Se [ 17 , 47 ]) under the same test conditions (bending radius of 4 mm, bending cycles of 1000 times), the Cu 2−x S 0.98 Se 0.02 film exhibits outstanding flexibility, which is mainly due to the excellent flexibility of nylon and the improvement in the density of the film.…”

“…Since μ is inversely proportional to m*, 𝜇 = 𝑞𝜏 𝑚 * ⁄ (q is the electric charge and τ is the carrier scattering time), the reduced m* after Se doping favors carrier transport, thereby increasing μ. Additionally, the m* of the T-Cu1.96S is higher than that of the M-Cu2S [33], which is the reason for the increase in m* from 3.09 me at y = 0.01 to 3.39 me at y = 0.03. [25,26,29,43] and flexible films [30,44,45] at room temperature.…”

A Novel PDMS-Based Flexible Thermoelectric Generator Fabricated by Ag2Se and PEDOT:PSS/Multi-Walled Carbon Nanotubes with High Output Performance Optimized by Embedded Eutectic Gallium–Indium Electrodes

“…However, FTEGs composed of Ag 2 Se and PEDOT:PSS/MWCNTs remains to be studied. On the device side, FTEGs can usually be classified into four types depending on their structure: π-type structure [ 17 ], Y-type structure [ 18 ], annular structure [ 19 , 20 , 21 ], and single-leg structure [ 22 ]. FTEGs with the Y-type structure exhibit uneven current and heat flow densities.…”