Unipolar Electron Transport Polymers: A Thiazole Based All-Electron Acceptor Approach

Abstract

Experimental details, synthesis and analysis of the monomers and polymers, additional figures, and additional characterization data (PDF).

A Defect‐Free Naphthalene Diimide Bithiazole Copolymer via Regioselective Direct Arylation Polycondensation

“…From a synthetic point of view, state‐of‐the‐art Stille or Suzuki polycondensations have been mostly applied to prepare BTz‐, and also NDI‐based, polymers. These synthetic transformations are currently being replaced by in many ways more attractive C‐H functionalization strategies.…”

Significant Difference in Semiconducting Properties of Isomeric All‐Acceptor Polymers Synthesized via Direct Arylation Polycondensation

“…[4,10] Thec ombination of two imide-functionalized arenes,NDI and TPD,was selected due to their strong electron acceptor characteristics and deep HOMO levels,w hich could facilitate the electron transport and efficiently block the hole injection, respectively. [4,10] Thec ombination of two imide-functionalized arenes,NDI and TPD,was selected due to their strong electron acceptor characteristics and deep HOMO levels,w hich could facilitate the electron transport and efficiently block the hole injection, respectively.…”

“…This polymer showed promising unipolar n-type charge transport properties with the m e of 0.22 cm 2 V À1 s À1 (Figure 1a left). [4] Very recently,G uo et al found that the all-acceptor homopolymers PDTzTI and PBTI1, consisting of only the bithiazolothienyl tetracarboxydiimide (DTzTI) unit and bithiophene imide (BTI), respectively,e xhibited unipolar n-type charge transport properties with the remarkable m e up to 3.71 cm 2 V À1 s À1 (Figure 1a right). [4] Very recently,G uo et al found that the all-acceptor homopolymers PDTzTI and PBTI1, consisting of only the bithiazolothienyl tetracarboxydiimide (DTzTI) unit and bithiophene imide (BTI), respectively,e xhibited unipolar n-type charge transport properties with the remarkable m e up to 3.71 cm 2 V À1 s À1 (Figure 1a right).…”

“…[2] However,t he development of high-performance unipolar n-type semiconducting polymers with the electron mobility (m e )a bove 1cm 2 V À1 s À1 still remains as ignificant challenge mainly due to the limited molecular design strategies and difficult synthesis. [4,5] As far as the energy levels are concerned, the all-acceptor approach can produce semiconducting polymers with both the highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) levels being deep.The deep HOMO levels suppress the hole accumulation and the deep (or low-lying) LUMO levels facilitate electron transport, therefore giving rise to the enhanced n-type charge transport characteristics with suppressed p-type properties.One of the early stage all-acceptor conjugated polymers was poly(benzothiadiazole) (polyBT), which was synthesized by the Ni-mediated Yamamoto coupling reaction of dibromobenzothiadiazole (Chart S1 ai n the Supporting Information). [4,5] As far as the energy levels are concerned, the all-acceptor approach can produce semiconducting polymers with both the highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) levels being deep.The deep HOMO levels suppress the hole accumulation and the deep (or low-lying) LUMO levels facilitate electron transport, therefore giving rise to the enhanced n-type charge transport characteristics with suppressed p-type properties.One of the early stage all-acceptor conjugated polymers was poly(benzothiadiazole) (polyBT), which was synthesized by the Ni-mediated Yamamoto coupling reaction of dibromobenzothiadiazole (Chart S1 ai n the Supporting Information).…”

“…[5h] This was probably due to the presence of numerous charge carrier traps that most likely arose from the structural defects.H owever,o ne of the most significant technical challenges for the development of such all-acceptor polymers is the limited choice of acceptor units,constraining the available acceptor combinations when designing and synthesizing new polymers.T his is due to the fact that many tin or boric acid ester derivatives of the acceptor units are usually unstable and difficult to synthesize. [4,5] As aconsequence,the molecular weights (M n )o ft he all-acceptor polymers were often lower than those of the donor-acceptor counter polymers. [4,5] As aconsequence,the molecular weights (M n )o ft he all-acceptor polymers were often lower than those of the donor-acceptor counter polymers.…”