Pyrazine-Flanked Diketopyrrolopyrrole (DPP): A New Polymer Building Block for High-Performance n-Type Organic Thermoelectrics

Abstract

n-Doped conjugated polymers usually show low electrical conductivities and low thermoelectric power factors, limiting their applications in n-type organic thermoelectrics. Here, we report the synthesis of a new diketopyrrolopyrrole (DPP) derivative, pyrazine-flanked DPP (PzDPP), with the deepest LUMO level in all the reported DPP derivatives. Based on PzDPP, a donor−acceptor copolymer, P(PzDPP-CT2), is synthesized. The polymer displays a deep LUMO energy level and strong interchain interaction with a short π−π stacking distance of 3.38 Å. When doped with n-dopant N-DMBI, P(PzDPP-CT2) exhibits high ntype electrical conductivities of up to 8.4 S cm −1 and power factors of up to 57.3 μW m −1 K −2 . These values are much higher than previously reported n-doped DPP polymers, and the power factor also ranks the highest in solution-processable n-doped conjugated polymers. These results suggest that PzDPP is a promising high-performance building block for n-type organic thermoelectrics and also highlight that, without sacrificing polymer interchain interactions, efficient n-doping can be realized in conjugated polymers with careful molecular engineering.

Random terpolymer based on thiophene-thiazolothiazole unit enabling efficient non-fullerene organic solar cells

“…5). Owing to the stronger electronegativity of the sp 2 -nitrogen atom on TTz unit, the highest occupied molecular orbital (HOMO) levels of the terpolymers efficiently decreased [39][40][41] , which could be beneficial to achieve higher V oc and lower energy loss (E loss ) in OSCs. Figure 1c and Supplementary Fig.…”

Synthesis of conjugated polymers via cyclopentannulation reaction: promising materials for iodine adsorption

“…The design of new conjugated polymers has become one of the chief topics of interest for scientific endeavors because of the importance of this latter class of materials in diverse applications, namely, light-emitting diodes (LEDs), [1][2][3] organic solar cells, [4][5][6][7] field-effect transistors (FETs), [8][9][10][11][12][13][14][15][16] sensors, 17 optical switches, [18][19][20][21][22] batteries, 23 and thermoelectrics. 24 In addition to the hitherto mentioned applications, conjugated microporous polymers (CMP) have become exceptionally eminent due to many reasons, notably their extended π-conjugation skeleton, high stability, synthesis versatility, large surface area, and excellent gas sorption properties. 25 The total world energy demand is increasing rapidly as a result of the rise in global population and economic growth.…”

The effect of aromatic ring size in electron deficient semiconducting polymers for n-type organic thermoelectrics

“…As a result, their thermoelectric figures of merit (ZT) exhibited high values in the range of 0.2-0.4, [7][8][9][10][11] comparable to the state-of-the-art inorganic (TE) materials. However, the conductivity of n-type electron-conducting polymers have been trailing behind their p-type counterparts, with few examples having achieved conductivities of over 1 S cm À1 , [12][13][14][15] This is predominantly arising from not exhibiting a large enough electron affinity (too shallow LUMO energy level) to facilitate electron transfer from n-dopant. A deep LUMO level is required to achieve an energy offset that allows electron transfer from the HOMO level of the dopant to the LUMO level of the polymer, thus facilitating the doping mechanism.…”