Optimal array alignment to deliver high performance in flexible conducting polymer-based thermoelectric devices

Flexible thermoelectric devices(F-TEDs)show great potentials to be applied in curved surface for power generation by harvesting low-grade energy from human body and other heat sources.However,their power generation efficiency is constrained by both unsatisfactory constituent materials performance and immature device design.Here,we used an optimal alignment of vertically-aligned poly(3,4-ethylenedioxythiophene)polystyrene sulfonate(PEDOT:PSS)arrays to assemble a 2.7×3.2 cm^(2)F-TEDs,exhibiting a maximum power output of 10.5μW.Such a high performance can be ascribed to the outstanding power factor of 198μW m^(-1)K^(-2)by the synergetic effect of both high charge mobility and optimal oxidation level and the optimized array alignment that maximizes the temperature difference utilization ratio across the TE legs.Particularly,optimized leg distance of 6 mm and leg length of 12 mm are determined to realize a high temperature difference utilization ratio of over 95%and a record-high output power density of 1.21μW cm^(-2)under a temperature difference of 30 K.Further,reliable bending(1000 cycles)and stability(240 h)tests indicate the outstanding mechanical robustness and environmental stability of the developed F-TEDs.This study indicates our reasonable device design concept and facile material treatment techniques secure high-performance F-TEDs,serving as a reference for other flexible energy harvesting devices with wide practical applications.

A flexible and smart shape memory alloy composite sheet based on efficient and bidirectional thermal management

Leveraging advances in shape memory alloys(SMAs)and flexible thermoelectric devices(f-TEDs),this paper presents a structural and functional integrity composite sheet to address the inefficient and bulky activation of 2-D SMAs.A series of experimental tests were performed to reveal the generation,change,and transfer mechan-isms of different types of electrically-induced heat in the f-TED,as well as the temperature-induced SMA phase transformation beha-viors.The results show that the composite sheet exhibited good bidirectional thermal management capacity.The austenite defor-mation can be completed within 10s at an operating current of 2 A.The cooling recovery,in particular,performs much better than in conventional modes(the temperature declines exponentially with time).Finally,through two functional prototypes,a light switch and a flexible gripper,the application potential of the proposed com-posite was further experimentally demonstrated.