PBDB-T Accessed via Direct C–H Arylation Polymerization for Organic Photovoltaic Application

Abstract

Poly[(2,thiophen-2-yl)-benzo-[1,2-b:4,5-b′] dithio-phene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione))] (PBDB-T), one of the most important donor polymers in organic photovoltaics (OPVs), is successfully synthesized, for the first time, via atom-economic direct C−H arylation polymerization (DArP). We systematically investigated the effects of reaction parameters on the molecular weights, polydispersity index, optical properties, device performance, and morphologies. Five batches of PBDB-T (P1−P5) with different molecular weights are synthesized under varied DArP conditions. Among them, P5 synthesized with the assistance of tetramethylethylenediamine (TMEDA) co-ligand shows the best performance for OPV device, yielding a 6.52% power conversion efficiency (PCE) in the bulk heterojunction pairing with ITIC. Briefly, an optimal DArP protocol toward PBDB-T has been developed in the current study, which will provide a guideline for the synthesis of high-performance OPV materials in an atom-economic way.

Inhibiting Mg Diffusion and Evaporation by Forming Mg‐Rich Reservoir at Grain Boundaries Improves the Thermal Stability of N‐Type Mg3Sb2 Thermoelectrics

“…[ 74,75 ] Compared with the MgB 2 ‐free sample ( x = 0), the κ lat shows a slight decreasing trend for the x = 0.01 sample, but shows an increasing trend for the samples with higher MgB 2 content ( x = 0.02–0.04). This phenomenon is quite like our previous reports on MgB 2 or B‐doped GeTe and Bi 2 Te 3 ‐based samples, [ 12,76–78 ] which should be ascribed to the tradeoff between the microstructures‐induced phonon scatterings (i.e., GB and secondary phases) and intrinsic high thermal conductivity of secondary phases of Mg‐B compounds and B dispersoids. In all, by adding MgB 2 , the ZT of the Mg 3.05 (Sb 0.75 Bi 0.25 ) 1.99 Te 0.01 (MgB 2 ) x is quite close to each other (Figure 5f), showing a slight enhancement.…”

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

“…[49][50][51] In recent years, direct C-H arylation (DACH) (i.e., C-H/C-Br cross coupling), has attracted increasing attention in the synthesis of π-functional materials owing to their outstanding merits of atomand step-economy, simplified procedures, environmental friendliness, and cost-effectiveness. [51][52][53][54][55] Till now, DACH coupling has been dominantly used in the synthesis of polymeric and molecular materials, while rarely employed to oligomeric materials except for our pioneering work on the DACH synthesizing π-COs. [48][49][50][51] In continuation of our previous efforts on DACH-derived π-functional materials, [37,[49][50][51][52][58][59][60][61][62] herein, a series of π-conjugated oligomeric acceptors & donor are facilely synthesized by an atomand step-economical, and labor-saving synthetic route. Firstly, the oligomeric key precursors (BTDT) n (n = 1-4, wherein "n" represents the number of repeating units) with stepwise increasing π-lengths were synthesized by a one-step DACH reaction, followed by Vilsmeier-Haack (V-H) and Knoevenagel reactions, and lastly afforded three oligomeric acceptor (BTDT) n -IC (n = 1-3) and one oligomeric donor (BTDT) 4 -RD (Scheme 1).…”

Perylene-diimide for organic solar cells: current scenario and prospects in molecular geometric, functionalization, and optoelectronic properties

“…[21][22][23][24][25][26][27][28][29] Additionally, very recently, researchers have developed n-type small molecular acceptors because NFA polymeric material is difficult to purify, has reduced solubility, is hard to characterize with an undened molecular weight, and has low inltration into the nanostructured material. [30][31][32][33][34][35][36] Depending on the degree of dispersion, they exhibit the organic small molecules used in OSCs can be classied as either monodispersed small molecules or polydispersed small molecules. This article offers up-tothe-minute insights into recently discovered organic molecular small molecule PDI variations; for example, methodologies that are necessary to enable possible scalable applications of OSCs.…”