Investigation of Structure–Property Relationships in Diketopyrrolopyrrole-Based Polymer Semiconductors via Side-Chain Engineering

Abstract

Systematic side-chain engineering has been performed for diketopyrrolopyrrole-selenophene vinylene selenophene (DPP-SVS) polymers to determine the optimal side-chain geometries for the most efficient charge transport, and the structure-property relationship has been thoroughly investigated using a range of analyses. A series of DPP-SVS polymers, ranging from 25-DPP-SVS to 32-DPP-SVS, with branched alkyl groups containing linear spacer groups from C2 to C9 has been synthesized, and the electrical performance of these polymers is significantly dependent on both the length of the spacer group and its odd-even characteristics. Spacer groups with even numbers of carbon atoms exhibit chargecarrier mobilities that are one order of magnitude higher than those with odd numbers of carbon atoms. The optimized charge transport has been obtained from 29-DPP-SVS with C6 spacer, showing the maximum mobility of 13.9 cm 2 V −1 s −1 (V GS , V DS = −100 V) and 17.8 cm 2 V −1 s −1 (V GS , V DS = −150 V). Longer spacer groups deviate from the odd-even trend. In addition to the exceptionally high charge-carrier mobilities of the DPP-SVS polymers, the results obtained herein provide new insight into the molecular design of high-performance polymer semiconductors.

Effects of branching position of alkyl side chains on ordering structure and charge transport property in thienothiophenedione- and quinacridone-based semiconducting polymers

“…[21][22][23][24][25] However, in most of these studies, branched alkyl groups are introduced into the N-position of limited cores, such as isoindigo and diketopyrrolopyrrole. [26][27][28] Here, to further systematically study the branching position effect, we introduced a series of branched alkyl groups with different branching positions (that is, 2-decyltetradecyl (2DT), 3-decylpentadecyl (3DP), 4-decylhexadecyl (4DH), and 5-decylheptadecyl (5DH) groups; Figure 1) into the 3-position of the thiophene ring and the N-position of QA (quinacridone). Then, the 3-alkylthiophenes were combined with the TTD (thienothiophene-2,5-dione) unit, which was copolymerized with the unsubstituted bithiophene unit (PTTD4Ts), and the alkylated QA units were also copolymerized with the unsubstituted bithiophene unit (PQA2Ts; Figure 1).…”

Effect of Chalcogens on Electronic and Photophysical Properties of Vinylene-Based Diketopyrrolopyrrole Copolymers

“…38−41 Kim and co-workers have demonstrated that charge carrier mobility in a vinylene linked thiophene DPP based copolymer can be improved with the substitution of selenophene. 28,42,43 Recently, the nature (p-and n-type) of the charge transport property was finely tuned by attaching a strong electron withdrawing group at the vinylene linkage in a DPP based copolymer. 44,45 Thus, the variety of results obtained for vinylene systems reveals that a clear and conclusive understanding is lacking about the role of the vinylene moiety in organic semiconductors.…”

Influence of the positions of thiophenes and side chains on diketopyrrolopyrrole based narrow band-gap small molecules for organic solar cells

“…Wang et al reported a narrow band gap small molecule based on DPP, showing an outstanding PCE of 7.00% [23]. In addition, Kim and coworkers synthesized a series of DPP-selenophene vinylene selenophene polymers with a maximum mobility of 17.8 cm 2 V À1 s À1 by the side chain engineering [24].…”