Development of a new conjugated polymer containing dialkoxynaphthalene for efficient polymer solar cells and organic thin film transistors

Abstract

A new semiconducting polymer, poly((5,5‐E‐α‐((2‐thienyl)methylene)‐2‐thiopheneacetonitrile)‐alt‐2,6‐[(1,5‐didecyloxy)naphthalene])) (PBTADN), an alternating copolymer of 2,3‐bis‐(thiophene‐2‐yl)‐acrylronitrile and didecyloxy naphthalene, is synthesized and used as an active material for organic thin film transistors (OTFTs) and organic solar cells. The incorporation of 2,3‐bis‐(thiophene‐2‐yl)‐acrylronitrile as an electron deficient group and didecyloxy naphthalene as an electron rich group resulted in a relatively low bandgap, high charge carrier mobility, and finally good photovoltaic performances of PBTADN solar cells. Because of the excellent miscibility of PBTADN and PC71BM, as confirmed by Grazing Incident X‐ray Scattering (GIXS) measurements and Transmission Electron Microscopy (TEM), homogeneous film morphology was achieved. The maximum power conversion efficiency of the PBTADN:PC71BM solar cell reached 2.9% with a Voc of 0.88 V, a short circuit current density (Jsc) of 5.6 mA/cm2, and a fill factor of 59.1%. The solution processed thin film transistor with PBTADN revealed a highest saturation mobility of 0.025 cm2/Vs with an on/off ratio of 104. The molecular weight dependence of the morphology, charge carrier mobility, and finally the photovoltaic performances were also studied and it was found that high molecular weight PBTADN has better self assembly characteristics, showing enhanced performance. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Dialkoxynaphthalene as an electron-rich unit for high-performance polymer solar cells with large open circuit voltages

“…Later on, Kwon et al developed two alternating copolymers based on the didecyloxynaphthalene and 2,3-bis-(thiophene-2-yl)acrylronitrile. When the two copolymers were used for polymer solar cells, a maximum PCE of 2.9% with a V oc of 0.88 V was achieved [24]. The relatively inferior photovoltaic performance of the dialkoxylnaphthalene-based copolymers could be attributed to the inappropriate selection of the acceptor unit, which leads to copolymers with low molecular weights or improper FMO energy levels.…”

Dithieno[2,3‐d:2',3'‐d']benzo[1,2‐b:4,5‐b']dithiophene (DTBDAT)‐based copolymers for high‐performance organic solar cells

“…Polymer solar cells (PSCs) have received growing attention in recent years owing to the flexible, colorful and low‐mass properties of the devices, and the broad range of potential small‐ and large‐area applications . PSCs typically employ bulk‐heterojunction (BHJ) architecture, and the power conversion efficiencies (PCEs) of PSCs that have thus far been achieved range from 1% to more than 9% .…”

“…Such fused aromatic rings typically exhibit excellent intermolecular charge‐ transport properties because of the planarity of the backbone. There have been several reports describing the high charge‐carrier mobilities of these moieties when used in organic field‐effect transistors . Derivatives of DTBDAT exhibit relatively low HOMO levels and large band gaps compared with those of other fused aromatic rings, which suggests that the DTBDAT motif is a particularly stable organic semiconductor.…”

Synthesis of Poly(benzothiadiazole‐co‐dithienobenzodithiophenes) and Effect of Thiophene Insertion for High‐Performance Polymer Solar Cells

“…On this basis, research groups have extensively developed conjugated polymers with alternating donor-acceptor (D-A) units to tune the energy levels by controlling the intramolecular charge transfer (ICT) from the donor to the acceptor moiety. [10][11][12][13][14][15] Among the various D-A conjugated polymers, benzo[1,2b:4,5-b']dithiophene (BDT) has been widely used as the donor unit for high-performance OPVs. [16][17][18][19] For example, the copolymerization of BDT with various acceptor units, such as thienoA C H T U N G T R E N N U N G [3,4-b]thiophene (TT), [17] thiophene-TT, [18] and N-alkylthienoA C H T U N G T R E N N U N G [3,4-c]pyrrole-4,6-dione (TPD), [19] has led to BDT-based conjugated polymers showing promising OPV performances.…”