Synthesis, Characterization, and Transistor and Solar Cell Applications of a Naphthobisthiadiazole-Based Semiconducting Polymer

Abstract

We report the synthesis and characterization of a novel donor-acceptor semiconducting polymer bearing naphthobisthiadiazole (NTz), a doubly benzothiadiazole (BTz)-fused ring, and its applications to organic field-effect transistors and bulk heterojunction solar cells. With NTz's highly π-extended structure and strong electron affinity, the NTz-based polymer (PNTz4T) affords a smaller bandgap and a deeper HOMO level than the BTz-based polymer (PBTz4T). PNTz4T exhibits not only high field-effect mobilities of ~0.56 cm(2)/(V s) but also high photovoltaic properties with power conversion efficiencies of ~6.3%, both of which are significantly high compared to those for PBTz4T. This is most likely due to the more suitable electronic properties and, importantly, the more highly ordered structure of PNTz4T in the thin film than that of PBTz4T, which might originate in the different symmetry between the cores. NTz, with centrosymmetry, can lead to a more linear backbone in the present polymer system than BTz with axisymmetry, which might be favorable for better molecular ordering. These results demonstrate great promise for using NTz as a bulding unit for high-performance semiconducting polymers for both transistors and solar cells.

Control of Phase Separation of Benzothienoisoindigo-Benzodithiophene Copolymer for Organic Photovoltaics

“…Liu et al reported analogous copolymer of quarterthiophene and fBT with 10.8% PCE by controlling morphology and crystallinity [8]. Polymer orientation and its gradient in the depth direction are important for improving hole transport and consequent device performance [9,10]. As such, Vohra et al have reported quarterthiophene and naphthothiadiazole (NTz) copolymer achieving 10.1% PCE [11].…”

Benzo[1,2-b:4,5-b′]dithiophene and benzotriazole based small molecule for solution-processed organic solar cells

“…Intensive interdisciplinary efforts have been dedicated to improving the power conversion efficiencies (PCEs) of solution-processed polymer bulk heterojunction (BHJ) solar cells [4][5][6][7][8][9][10]. More recently, BHJ OSCs using solution-processed small molecules as donors have also attracted increasing attentions [11][12][13][14][15].…”

Benzothiadiazole[1,2-b:4,3-b′]dithiophene, a new ladder-type multifused block: Synthesis and photovoltaic application

“…For instance, covalently fastening adjacent aromatic units, the polymer could have enhanced effective p-conjugation, lower bandgap, and strong light-harvesting, which induce p-p stacking and facilitate the charge transport by intermolecular hopping [23][24][25][26]. Therefore, fused-ring building blocks are widely used in synthesis of conjugated polymers, such as naphtho [2,3-b:6,7-d 0 ]dithiophene (NDT) [27], thienyl-phenylene-thienylene-phenylene-thienyl (TPTPT) [28], indaceno dithiophene (IDTT) [29], naphtho-[1,2-c:5,6-c]bis [1,2,5]-thiadiazole (NT) [30,31]. Cheng et al reported a multifused DTPBT unit (Scheme 1) [32], which was prepared by covalently fastening adjacent electron-rich donor (thieno [3,2-b]pyrrole) and electron-deficient acceptor (BT).…”