Brønsted Acid Doping of P3HT with Largely Soluble Tris(pentafluorophenyl)borane for Highly Conductive and Stable Organic Thermoelectrics Via One‐Step Solution Mixing

Abstract

Molecular doping is essential for improving the thermoelectric properties of conjugated polymers, but dopants of low solubility either restrict the formation of high quality films or complicate fabrication steps. Although a highly soluble molecular dopant, tris(pentafluorophenyl)borane (BCF), has been sporadically studied, its potential has not yet been fully explored. Herein, particularly intriguing effects of Brønsted acid doping with BCF‐water complexes for poly(3‐hexylthiophene) (P3HT) are reported, which can facilitate substantial increases in electrical and thermoelectric properties with remarkable doping stabilities. Interestingly, a unique polymorph of P3HT with interdigitated alkyl chains (called type II) is observed in the Brønsted acid doping with BCF‐water complexes. Moreover, the doped P3HT shows conformational change to the quinoid structure, enabling increased backbone planarity. As a result, the Brønsted acid‐doped P3HT films exhibit outstanding electrical conductivities, thermoelectric power factors, and figure‐of‐merit of up to 33.0 S cm−1, 28.3 µW m−1 K−2, and 0.034, respectively. These values are at least an order of magnitude higher than those of P3HT films doped with a conventional molecular dopant, 7,7,8,8‐tetracyano‐2,3,5,6‐tetrafluoroquinodimethane. The Brønsted acid doping with BCF‐water complexes also affords excellent air stabilities of P3HT films, which potentially provides a strong comparative advantage over existing highly reactive salt‐type dopants, such as FeCl3.

Achieving Efficient p‐Type Organic Thermoelectrics by Modulation of Acceptor Unit in Photovoltaic π‐Conjugated Copolymers

“…Meanwhile, the strong electron-withdrawing capability of A moiety could strengthen the energetic disorder along the polymer chains and tuning the shape of density-ofstates (DOS), thus enlarging the value of E F − E T , which is proportional to S. [27] Accordingly, the peak room-temperature PFs of PBDP-T, PTB7-Th, and PBDB-T are acquired to be as high as 20.1, 46.0, and 105.5 μW m −1 K −2 at [FeCl 3 ] = 10, 5, and 10 mM, respectively, as shown in Figure 4c. When comparing with the literature results of D-𝜋, [14][15][16][17][18][19][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] A-𝜋, [20,[49][50][51] and D-A [23][24][25][26][27][52][53][54] type copolymers as summarized in Figure 4d, it has been rarely reported with S values over 100 μV K −1 , most of which were obtained by those D-A copolymers. This work achieves an impressively high PF over 100 μW m −1 K −2 while preserving a superior S beyond 200 μV K −1 as shown in Table S6, Supporting Information, holding great promise in wearable skin electronics, taken as one example.…”

Tris(pentafluorophenyl)borane‐Modified P3CT‐K as an Efficient Hole‐Transport Layer for Inverted Planar MAPbI3 Perovskite Solar Cells

“…Meanwhile, the CH out-of-plane bending vibration peak of thiophene in P3CT-K shifts from 820 to 816 cm −1 , which suggests the coordination interaction between the lone pair of the thiophene and the empty p-orbital of TPB, as has been reported. [23][24][25] The UV-vis absorption spectra of P3CT-K with or without TPB are shown in Figure 1b. The absorption peak of P3CT-K(TPB) displays an obvious blueshift from 546 to 517 nm comparing with that of P3CT-K after TPB addition.…”

Recent Progress in Conducting Polymer Composite/Nanofiber-Based Strain and Pressure Sensors

“…However, the resultant polymer exhibits poor solubility in the solvents, thereby restricting the applicability. Following this, Bronsted acid and Lewis acid dopants comparative studies revealed that the Bronsted acid doped P3HT lead to the delocalized length increase because of enhanced crystallinity and backbone planarization contributions [156]. As an alternative approach, molecular structure and crystallinity fine-tunements of the polythiophene remains crucial in glorifying the high charge carrier mobility of the transistors.…”