Synthesis of Long‐Chain Oligomeric Donor and Acceptors via Direct Arylation for Organic Solar Cells^†

Abstract

Comprehensive SummaryThe rapid synthesis of structurally complicated electron donors & acceptors still remains a major challenge in organic solar cells (OSC). In this work, we developed a highly efficient strategy to access long‐chain oligomeric donor and acceptors for OSC applications. A series of cyclopentadithiophene (CPDT) and benzothiadiazole (BT)‐based π‐conjugated oligomers, i.e., three oligomeric acceptors (BTDT)n‐IC (n= 1‐3) and one long‐chain oligomeric donor (BTDT)4‐RD, are facilely synthesized by an atom‐ and step‐economical, and labor‐saving direct C−H arylation (DACH) reaction (i.e., C−H/C−Br cross coupling). Note that (BTDT)4‐RD involving five CPDT, four BT and two rhodamine (RD) building blocks is the longest oligomeric donor in the fullerene‐free OSC devices ever reported. The dependence of the structure‐property‐performance correlation of (BTDT)n‐IC (n = 1‐3) and (BTDT)4‐RD on the π‐conjugation lengths are thoroughly investigated by opto‐electrochemical measurements, bulk heterojunction (BHJ) OSC devices and microscopies. The (BTDT)1‐IC:PBDB‐T and (BTDT)4‐RD:Y6 BHJs achieve power conversion efficiencies of 9.14% and 4.51%, respectively. Our findings demonstrate that DACH reaction is a powerful tool to tune the opto‐electronic properties and device performances by regulating the lengths of π‐conjugated oligomers with varied numbers of repeating units.This article is protected by copyright. All rights reserved.

Functionalized Linear Conjugated Polymer/TiO2 Heterojunctions for Significantly Enhancing Photocatalytic H2 Evolution

“…On the basis of our previous well-developed Pd-catalyzed direct C–H arylation polymerization strategy (DArP) [ 32 , 56 , 57 ], three pristine LCPs denoted as TFl , TS and TSO 2 showed in Scheme 1 a were prepared by treatment of corresponding dibromo-precursors, 2,2-biothiophene via DArP methods, as detailed in the supporting information . Accordingly, the CP@TiO 2 heterojunctions ( TFl@TiO 2 , TS@TiO 2 and TSO 2 @TiO 2 , Scheme 1 b) were fabricated via in situ DArP between appropriate dibromides, 2,2-biothiophene in the presence of TiO 2 .…”

“…Taking TSO 2 @TiO 2 as an example, anhydrous toluene (8 mL) was added to a Schlenk tube containing 3,7-dibromobenzothiophene-S, S-dioxide (40.0 mg, 1 eq), 2,2-biothiophene (19.7 mg, 1 eq), Cs 2 CO 3 (77.1 mg, 2 eq), PivOH (3.6 mg, 30 mol%), P(o-MeOPh) 3 (2.5 mg, 6 mol%), Pd 2 (dba) 3 (3.2 mg, 3 mol%) and TiO 2 (81.0 mg). Then, the resulting mixture was stirred in an oil bath at 100 • C under an argon atmosphere for 48 h. After the reaction was completed, the desired TSO 2 @TiO 2 heterojunction was obtained by filtration, followed by continuous washing with dichloromethane-methanol-water and finally drying at 80 On the basis of our previous well-developed Pd-catalyzed direct C-H arylation polymerization strategy (DArP) [32,56,57], three pristine LCPs denoted as TFl, TS and TSO2 showed in Scheme 1a were prepared by treatment of corresponding dibromo-precursors, 2,2-biothiophene via DArP methods, as detailed in the supporting information. Accordingly, the CP@TiO2 heterojunctions (TFl@TiO2, TS@TiO2 and TSO2@TiO2, Scheme 1b) were fabricated via in situ DArP between appropriate dibromides, 2,2-biothiophene in the presence of TiO2.…”

Accessing Poly(DA-ran-Dπ) Ternary Copolymers via Direct C–H Arylation for Ultrahigh Photocatalytic Hydrogen Production

“…In recent years, the boron- and tin-free DArP (i.e., the straightforward C–H/C–Br coupling) has emerged as a green and atom-economical alternative to the traditional Suzuki and Stille C–M/C–Br (M = B and Sn) couplings. − Here, the Pd-catalyzed DArP ,, (Scheme ) among DBTSO 2 , EDOT, and 1,4-dibromobenzene (DBB) led to the formation of five target LCPs EDBz-0 , EDBz-25 , EDBz-50 , EDBz-75 , and EBz-100 , wherein 0, 25, 50, 75, and 100 represent the percentages of phenyl units involved. By varying the feed ratios of DBB, the ternary LCPs incorporating different contents of the phenyl π-spacer and DBTSO 2 were facilely obtained (Scheme ).…”

Advancing Integration of Direct C–H Arylation-Derived Star-Shaped Oligomers as Second Acceptors for Ternary Organic Solar Cells

“…As part of these reactions, the coupling of C–M/C–Br occurs, where M might be either B or Sn. − In order to create reliable, economical, and time-saving ways to produce UNFRAs, it is essential to tackle these reactions to avoid the prefunctionalization of C–M bonds. − Direct C–H arylation (DACH), also known as C–H/C–Br cross-coupling, is becoming more popular as a way to formulate organic semiconductor compounds, − owing to its outstanding benefits, including atom- and step-economy, simplified techniques, low environmental impact, and cost-effectiveness. The importance of DACH in OSC research stems from the fact that it is used in the synthesis of a wide variety of oligomers, including linear and nonlinear ones, as well as star oligomers, and polymeric and molecular materials. − …”