Transparent flexible thermoelectric material based on non-toxic earth-abundant p-type copper iodide thin film

Abstract

Thermoelectric devices that are flexible and optically transparent hold unique promise for future electronics. However, development of invisible thermoelectric elements is hindered by the lack of p-type transparent thermoelectric materials. Here we present the superior room-temperature thermoelectric performance of p-type transparent copper iodide (CuI) thin films. Large Seebeck coefficients and power factors of the obtained CuI thin films are analysed based on a single-band model. The low-thermal conductivity of the CuI films is attributed to a combined effect of the heavy element iodine and strong phonon scattering. Accordingly, we achieve a large thermoelectric figure of merit of ZT=0.21 at 300 K for the CuI films, which is three orders of magnitude higher compared with state-of-the-art p-type transparent materials. A transparent and flexible CuI-based thermoelectric element is demonstrated. Our findings open a path for multifunctional technologies combing transparent electronics, flexible electronics and thermoelectricity.

Flexible Thermoelectric Materials and Generators: Challenges and Innovations

“…Reactive sputtering has additional advantages as it can be conducted at room temperature, which enables the application of various organic flexible substrates . A typical example can be found from CuI thin films fabricated on a flexible PET substrate . Figure a shows an optical image of a flexible CuI thin film on the PET substrate.…”

Design, Performance, and Application of Thermoelectric Nanogenerators

“…e) The actual photograph of a CuI thin film sample deposited on PET with a bending angle. Reproduced with permission . Copyright 2017, Nature Publishing Group.…”

“…Figure e,f displays two kinds of flexible TEGs that are made of transparent thin film of polycrystalline CuI and few‐layer graphene film, respectively. As TE materials, polycrystalline CuI and few‐layer graphene are deposited on flexible substrates by sputtering and inkjet printing . These kinds of TEGs show excellent flexibility, including bending and torsion, thermostability, and durability of mechanical antideformations.…”

“…Recently, flexible TEGs have gradually attracted increasing attention in the novel research works and potential applications. According to the deformation characteristics, flexible TEGs specifically include stretchable, compressible, and bendable TEGs, among others . Furthermore, most of them possess the characteristics of light weight, small volume, easy to carry, and low production cost.…”

Design of Substrate Stretchability Using Origami-Like Folding Deformation for Flexible Thermoelectric Generator

“…However, a flexible TE generator is required as there is frequently a need to attach generators to a heat source with a non-flat surface, such as piping or the human body. Recently, TE generators with bendability [3,4,5,6,7,8,9,10,11,12] and/or stretchability [13] were developed by using a deformable TE element (e.g., a carbon nanotube (CNT)-polystyrene (PS) composite) or a rubber-based stretchable substrate (e.g., polydimethylsiloxane (PDMS)). However, deformable TE conversion materials based on polymer composites unfortunately have inferior TE conversion efficiency compared to the rigid BiTe-based TE conversion materials, while the stretchable substrates using rubber have a narrow usable temperature range of 213–423 K [14].…”