Organic Thermoelectric Materials: Niche Harvester of Thermal Energy

Abstract

Organic thermoelectric (OTE) materials promise convenient energy conversion between heat gradients and voltage with flexible and wearable powersupplying devices at a low price. Although a variety of OTE materials are investigated, the TE performance is still far from practical application. To achieve high TE performance, a thorough understanding of the structureproperty relationship in OTE materials is necessary. In this comprehensive review, the fundamentals of OTEs are summarized, the recent achievements of OTE materials are reviewed, and the relationship between structure and properties in high-performance OTE materials is discussed. Furthermore, how the molecular backbones, side chains, energy levels, molecular packing, and heteroatom effect all play vital roles in thermoelectric properties is addressed. Finally, the future direction of research on OTE materials is envisaged.

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“…The energy conversion efficiency [ 12 , 13 ] is determined by the ZT value, and the temperature difference between hot and cold ends as follows: where T h represents the temperature of the hot side of TEG, and T c represents the temperature of the cold side of TEG. The higher temperature differences can produce higher conversion efficiency and performance output.…”

Optimizing the doping efficiency and thermoelectric properties of isoindigo-based conjugated polymers using side chain engineering

“…Therefore, considerable research efforts have been devoted to investigating the thermoelectric properties of these polymers, with the goal of improving their performance and developing new applications. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Inherently conjugated polymers exhibit relatively low s, and chemical doping, which occurs alongside the charge transfer between the host polymer and dopant molecules, is indispensable for increasing the carrier concentration in doped polymer films. The dopants (usually FeCl 3 [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] and 7,7,8,8-tetracyanoquinodimethane (TCNQ) [42][43][44][45][46][47][48][49][50][51][52][53][54] derivative...…”

“…Therefore, considerable research efforts have been devoted to investigating the thermoelectric properties of these polymers, with the goal of improving their performance and developing new applications. 8–25…”

Realizing p‐Type and n‐Type Doping of a Single Conjugated Polymer via Incorporation of a Thienoisatin‐Terminated Quinoidal Unit

“…Conjugated polymers (CPs) are promising organic thermoelectric (OTE) materials because of their diverse molecular structures, good flexibility, low thermal conductivity, and excellent solution processability. [ 1–6 ] For the construction of thermoelectric apparatus, both p ‐type and n ‐type conductive materials are required. [ 7–14 ] Therefore, in the past several decades, many high‐performance p ‐type and n ‐type OTE materials have been developed by doping different types of CPs.…”