Recent Advances and Prospects of Small Molecular Organic Thermoelectric Materials

Abstract

Thermoelectric (TE) materials possess unique energy conversion capabilities between heat and electrical energy. Small organic semiconductors have aroused widespread attention for the fabrication of TE devices due to their advantages of low toxicity, large area, light weight, and easy fabrication. However, the low TE properties hinder their large‐scale commercial application. Herein, the basic knowledge about TE materials, including parameters affecting the TE performance and the remaining challenges of the organic thermoelectric (OTE) materials, are initially summarized in detail. Second, the optimization strategies of power factor, including the selection and design of dopants and structural modification of the dope‐host are introduced. Third, some achievements of p‐ and n‐type small molecular OTE materials are highlighted to briefly provide their future developing trend; finally, insights on the future development of OTE materials are also provided in this study.

Chemical approaches for electronic doping in photovoltaic materials beyond crystalline silicon

“…Though its E A was lower than that of TCNQ, 24 the DDQ had high solubility with good processability, leading to easy and efficient doping. [225][226][227] In contrast, HAT-CN had poor solution processability due to its larger and rigid planar structure. 228 However, comparing with the above micromolecule dopants, HAT-CN was relatively stable without noticeable diffusion.…”

“…With an E A of À5.87 eV, CN6-CP has become the strongest p-type dopant in the recent literature for OPV. 227,229,230 Although this neutral molecule has been reported to be insoluble and highly reactive, they appeared to be stable and soluble when mixed with conductive polymers, such as the PDPP(6-DO) 2 TT, in CH 2 Cl 2 . And the conductivity of PDPP(6-DO) 2 TT was promoted from 10 À6 O À1 cm À1 to 30-70 O À1 cm À1 after doping by CN6-CP.…”

Enhancing the Performance of N‐Type Thermoelectric Devices via Tuning the Crystallinity of Small Molecule Semiconductors

“…Besides, the synthesis, modification, and purification of small molecules are relatively easier, making them promising candidates for organic thermoelectric devices. [ 21 , 22 , 23 ] In the construction of n‐type organic semiconductors, much attention was paid to the strongly electron‐deficient naphthalene bis‐isatin (NB) building block for its application in the field of organic thermoelectric devices, organic field‐effect transistors, and organic electrochemical transistors. [ 24 , 25 , 26 ] Materials constructed by naphthalene bis‐isatin building blocks are linked by a double bond, which can form a rigid backbone and avoid the rotation between adjacent aromatic rings.…”

Role of Pb Doping on the Thermoelectric Properties of Mg3Sb1.8‐yBi0.2Pby Alloys

“…[7][8] Ideal thermoelectric materials not only should possess high thermoelectric performance, but also meet the requirements of non-toxic, good chemical stability, and thermal stability in practical applications. [9][10][11][12][13][14][15] Nowadays, many tellurides have been developed as state-of-the-art thermoelectric materials, such as Bi 2 Te 3 , PbTe, SnTe and GeTe-AgSbTe 2 . [16][17][18][19][20][21] However, these materials contain the common toxic and scarce tellurium, which serves as the main constraint for their large-scale applications.…”

“…On the other hand, the environmental compatibility, raw material cost and service performance of thermoelectric materials have aroused great attention in recent years [7–8] . Ideal thermoelectric materials not only should possess high thermoelectric performance, but also meet the requirements of non‐toxic, good chemical stability, and thermal stability in practical applications [9–15] . Nowadays, many tellurides have been developed as state‐of‐the‐art thermoelectric materials, such as Bi 2 Te 3 , PbTe, SnTe and GeTe‐AgSbTe 2 [16–21] .…”